THIS coming Friday, on August 15, 2008, Carol Campbell will attend the opening of an exhibition of paintings at Glasgow School of Art (GSA). In an ordinary year she would look forward to such an event. But this has not been an ordinary year. On Wednesday August 15 2007 she lost her husband, the painter Steven Campbell, to a ruptured appendix. He was 54. The GSA exhibition, and a companion show at Glasgow Print Studio, will put on display a selection of the work he had completed at the time of his death.

Friends are coming from all four points to attend the private view: from London, Orkney, Edinburgh and also from New York, where the Campbells lived in the 1980s and where Steven Campbell made his name as an iconoclastic and powerful figurative painter. A piece of music called The Campbell Variations has been composed and will be performed at the private view by the Mark Sheridan Ensemble. Meanwhile, amid the lights and the clamour, guests, onlookers and students will swarm around a collection which reprises familiar themes - threat, symbolism, mystery - but which also hints at new directions and exciting potential.

"I know I'll be emotional about it," says Carol Campbell. "Even when he was alive I was emotional walking into a show, and being there to celebrate it you'd have tears coming into your eyes because you'd be so immensely proud. And there's no doubt it'll be incredibly sad and poignant to know that he's not standing there to be part of it."

But, she adds, it's two days before the private view that the family will really grieve. Campbell died on a Wednesday and, though the date doesn't coincide, it's the day itself that has the real, terrible resonance.

"For us the day for real mourning and thought will be the Wednesday. That was the day we sat by his bed. So in some ways it's good we have our private grief for just the plain fact that we miss him."

She is talking in the kitchen of the home they shared near Stirling and where their three children - Lauren, Greer and Rory - grew up. The house is an old mill, arrived at down a leafy road and bordered by a stream which should be reduced to a summer whisper today. Instead it's roaring with run-off from rain that has fallen hard for hours. It's a beautiful spot nonetheless, a Sylvan glade such as you might find in a painting by one of Campbell's heroes - Cezanne, perhaps, or Manet.

Carol Campbell has just returned from holiday in France, a chance to catch her breath before the show. She hates flying so she drove all the way there and back. She has been in the house barely an hour and the glass of vodka she poured for her husband before she left is gathering dust at the head of the table. It's a ritual she's developed, putting out a drink for him on the occasions she has one. Tears fill her eyes and a brief silence descends, one of several such interludes in our conversation.

Later, she will show me a wall cabinet full of things Steven collected. There's his father's pipe, a pen he bought on holiday because he liked the wolf design it bore, well-thumbed paperbacks, a Japanese scarf, a broken clock. It's a case of junkshop finds, mementoes, curios and keepsakes - the stuff of a life with its pockets emptied.

Over in the studio, meanwhile, I'll see the dregs of a glass of wine left by the children from the sleepless watch they kept there the night their father died. It sits atop a pile of books - Tintin, an encyclopaedia of hairdressing, a biography of Van Gogh - in a room dominated by a massive unfinished canvas, an old sofa, and a table whose top has been turned into a colourful lunar landscape by hardened tufts of oil paint. Tubes of the stuff lie about, many still holding the shape of their last squeeze, presumably from Campbell's own fingers.

The vodka, the wine, the paints, the cabinet both house and studio, it seems, are full of such votive offerings. Everyone deals with bereavement differently and for Carol Campbell these things help hold the memory of her husband close to her even though they ensure the pain stays raw.

"I don't want to file my emotions away in a wee box and say that's me got through the first anniversary of his death," she tells me. "I'm not deliberately standing back from life and not taking part in things, and yes I acknowledge that my life moves on. But I always, always want to feel that strong connection with Steven and I quite like the rawness of the grief because it keeps him here with me. I don't want my life to move on to the point where he's in my past. I don't want him to ever be in my past. He's in my every waking moment."

At the moment Steven Campbell is very much in her future as well. The GSA show utilises 11 of the 30 canvases he completed, which means there is still a sizeable cache of unseen paintings, as well as drawings and works on paper. They have all gone into safe storage and will be released as the artist's widow sees fit, though the hope - and, indeed, the expectation - is that the National Galleries of Scotland will mount a definitive retrospective at some point in the not-too-distant future. To that end, negotiations have been opened.

Carol Campbell is very aware that she is the keeper of her late husband's legacy and that, with five years to go until she retires from her job as a primary school teacher, she will be spending more and more time archiving and detailing the remaining work. But she is anxious to do it, anxious that the death of her husband at a relatively young age won't affect critical evaluation of the impact he had on the Scottish art scene, or diminish the revitalising energy he gave it - an energy that is still being felt 25 years after he graduated from the same art school that will this week honour his memory.

It seems unlikely, however, that his star will fade. Steven Campbell himself once said that the only thing that really connected him with Peter Howson, Ken Currie, Adrian Wiszniewski and Stephen Conroy - the other members of the so-called New Glasgow Boys - was a keen sense of rivalry. True or not, their names and their work have entered the national consciousness together like few artists before or since.

I ask her what it is about her husband's work that so captured the public's imagination. "All of human emotion is there in his paintings," she replies. "There are funny, quirky bits, little oddities, and a dark side, a Hieronymous Bosch side. I think maybe it's that. People look at them and recognise something of themselves. It's also because they are not finite. They are not saying This is the only way to understand this painting'. They are ambiguous enough to let the viewer bring their own ideas. I think that captures the public imagination too - and of course there are those great titles."

The titles are, indeed, magnificent, almost works of art in their own right. Portrait Of Two Cousins With The Same Mother Who Left Them Alone When She Was Seventeen is unsettling enough to have the emotions firing even before the painting has been viewed. Others, such as I Dreamt I Shot Mussolini At Cowes Week or (from the new exhibition) The Childhood Bedroom Of Captain Hook, are funny and fantastical. It's no surprise, then, that when asked to title the untitled paintings for the Glasgow shows, Carol Campbell refused. How do you follow Portrait Of Rorschach Testing Himself And Finding Himself Guilty?

In Steven Campbell's obituary in The Guardian, the GSA's former head of painting Sandy Moffat wrote that he "lived dangerously". An apt description? Carol Campbell chews on the question for a moment.

"He lived as a romantic artist and I think he pushed himself to great lengths for his art," she says. "I think in his work he really examined human emotions very deeply and never shied away from things. Most of us know there's a darker side to the human psyche but don't want to go there. Steven, in the studio, was never afraid to. So in that respect I do think he put himself in emotionally dangerous places from which to draw out the art he wanted to create."

But if that appears to describe a man of intense emotions and unpredictable behaviour, stripped to the waist and painting maniacally through the night, the truth is a little more prosaic: Steven Campbell was a nine-to-fiver and a devoted family man. After four years in New York in the mid-1980s during which time they hobnobbed with Yoko Ono, met the artists Jean-Michel Basquiat and Keith Haring, and hung out with Grandmaster Flash, the couple returned to Scotland to bring up their eldest daughter, Lauren, now 24. Greer and Rory followed - now 21 and 20 respectively - and at one point they took all three children out of school and travelled round Europe in a camper van for six months. On another occasion, when Carol had taken the children on holiday without their father for the first time, they returned to find the road down to the house festooned with lights.

"Steven had lit candles all the way down the driveway here and when we came back into the house he said he'd lit them so that they would guide us home. Now how many men do that kind of thing?"

For Campbell, family life was a welcome escape from rigours of the studio. He would drift home in the early evening - a journey of about 10 yards, though the gap between his imaginative creations and his kitchen was considerably wider - and gradually filter back in to the world of pony lessons, dance classes and Boy's Brigade outings. It was, says Carol, "a release" and the marriage worked exactly because of the differences: he was a dreamer and she is a doer. "I loved the man but I loved the artist as well," she says. "So the two us were really a great meeting because he gave my life what it would have lacked, which was that romantic sparkle and imagination."

In a canon dominated by symbolism and death, it's perhaps appropriate that Steven Campbell's last paintings feature a haunting intimation of his own end. It's a bottle of Gaviscon, the heartburn remedy, which he had been taking for the stomach pain which had affected him for some time but which now seems to have been the start of the appendicitis. The paintings themselves were intended as a tribute to Cezanne but they will now take on a different meaning.

"Steven was of the opinion that if you had toothache you took painkillers and after three days it went away. If you immersed yourself in your work, things always righted. He always felt he could work through anything and he had nothing to disprove that. So although he did have a lot of stomach pain the Gaviscon seemed to help."

Does she feel anger that her husband died from a condition that is not usually fatal? "I don't know if I feel anger," she says. "I feel sad and to a degree I feel guilty. If I had made him go to a doctor But I don't like doctors either. I think we were both the same. Yes, hindsight's a great thing but at the time you just think it's going to go away. So no I don't feel anger, I feel regret and remorse. Yes I would do it differently if I could do it again, but I can't."

What she can do is walk into Friday's private view with her head high, safe in the knowledge that her late husband's reputation will be bolstered by these last works. She may hope too that sight of them will light a flame in a young mind, just as one ignited in Steven Campbell's mind over a quarter of a century ago when he entered GSA as a mature student.

"We had a very pivotal conversation at a bus stop once," she recalls. "Steven said, There's something inside me. I don't know what it is but I know I've got to do something and I've not found it yet. But when I do I'll be damned good at it'."

For him, becoming a painter marked the end of that search and, equally, the start of a journey that produced some of the finest and most thought-provoking Scottish art of the 20th century. The journey was stopped tragically short of course but, as Steven Campbell showed during his years on the road, he really was damned good. He should savour the glass of vodka his wife will leave out for him on Friday - he certainly deserves it.