Josephine Hart: "The response to The Truth About Love has been balm to the soul"

It would be easy to make assumptions about Josephine Hart. Married to Maurice Saatchi, she is well heeled and well connected. Extremely well heeled, in fact – the couple have homes in Mayfair, Sussex and France. And extremely well connected. At the launch party for her new novel, The Truth About Love, I recognised pretty much everyone. But I didn't, I realised before rushing up to say hello, actually know them. Bob Geldof. Charles Dance. Princess Michael of Kent. The room – a chandeliered, walnut-panelled drawing room in a grand mansion round the corner from her home – had the quiet buzz of serious celebrity and serious money. This, you couldn't help feeling as you sipped champagne and tried not to feel like a child at the grown-ups' table, was exactly what people meant when they talked about "the establishment".

It's a feeling that continues when you go to interview Josephine Hart. A uniformed guard ushers you through grounds, a stone's throw from one of London's busiest streets, that have the feel of a Renaissance Italian garden. So this is what money gets you, you think, as you drink in the silence, and as you arrive at a grand front door and are led into a sitting room so uniformly, immaculately cream that the very thought of the coffee you've been offered brings you out in a cold sweat. And on the walls are what look like Renaissance frescoes, and the mad thought strikes you that maybe they are real Renaissance frescoes, but they couldn't be, could they?

"This was the set that Oscar Wilde mentioned in The Importance of Being Earnest," says Josephine Hart, in that lilting, emphatic Irish voice, and you just think, that's perfect. Perfect that this intense little woman, with dramatically dark hair and blazing blue eyes, should live in a real place mentioned in a fictional entity by one of the most famous Irish writers of all time. For Hart, it swiftly becomes clear, is passionate about literature, and passionate about poetry. Words that Burn is the title of her most recent poetry anthology (a quote from Thomas Gray) and it could be her motto. "Poetry spoken aloud and spoken well is riveting," she volunteers. "It is the very opposite of what people think."

She certainly ought to know. Hart first started organising public poetry-readings in an art gallery in Cork Street in the late Eighties and somehow persuaded a galaxy of theatrical luminaries – Alan Bates, Robert Stephens, Eileen Atkins, Edward Fox – to take part. The readings took off big time and even led to an Eliot programme, Let Us Go, Then, You and I, which started off as a one-off event at the Lyric, Hammersmith and turned into a six-week run – the first ever for a poetry programme – in the West End. She now hosts a monthly Josephine Hart Poetry Hour at the British Library. Participants – unpaid, apparently – have included Bono, Simon Callow, Brian Cox, Ralph Fiennes, Jeremy Irons, Roger Moore, Harriet Walter and Greg Wise. A way of sugaring the poetry pill, perhaps, except that Hart doesn't think it needs sugaring at all.

"You know, there are people who say, 'My boyfriend or girlfriend insisted I come to this, how can I get through it?' and then people are mesmerised because I suppose I pick pretty dramatic stuff and make people tremble, in a sense, on the edge of what's possible in life, and at some of the events people weep." Josephine Hart, it's clear from the glint in her eyes, is a missionary. In the beginning was the word and the word was God. Whatever the nuns taught her, at the Presentation Convent in County Westmeath, about sin and damnation and benediction and absolution, it's the words, in the reams of poetry she learnt by heart, that are seared on her soul, seared on her heart. "Until you can feel all those rhythms in your body through a sense of hearing," she says, "it's almost impossible to try to get what the poet was trying to do."

You might assume that this poetry lark was a hobby, a handy conversational opener at dinner parties, a classy little pastime for a lady who lunches. But Hart has never been a lady who lunches, or at least a lady who only lunches. When she met Saatchi, she was a highly successful director of a magazine publishing company, who then branched out into theatre productions in the West End. And the two poetry anthologies she has published, Catching Life by the Throat and Words that Burn, aren't just pretty collections of favourite poems, but passionate and highly analytical forays into territory – Elizabeth Bishop, Robert Frost – that really isn't for the faint-hearted. Most importantly, however, she isn't just a willing receptacle (or bared heart) for words that burn. Her own words can burn, too.

Damage, the novel she wrote in 1990 about a politician who has an affair with his son's fiancée, was (perhaps appropriately for a spouse of a Saatchi) a sensation. Hailed by Ted Hughes as "really a poem", and by The Washington Post as a masterpiece, it became a bestseller and was made into a film with Jeremy Irons and Juliette Binoche. I had assumed it was a sensation born out of sensationalism, but when I read it, I discovered I was wrong. It's deeply chilling, a novel that literally makes you gasp. "I would never have imagined in a million years what happened," Hart says. "I had no idea it was going to disturb people so much."

She wrote the first two chapters in a single morning after Maurice had shepherded her to the study of their house in Sussex and told her to just get on and write. A few weeks later, she'd finished it. Since then, she has written four more – Sin, Oblivion, The Stillest Day and The Reconstructionist. They all deal with primal themes – lust, cruelty, betrayal, revenge – and are all shot through with the same kind of intensity, but none, I'm afraid, is in quite the same league as that blistering first blast. In quite the same league, that is, until now.

The Truth About Love has been described by that great (and Booker-winning) Irish writer John Banville as "an ambitious and poetic weaving of a long-ago family tragedy into the tragic history, and histories of our time" – and that's exactly what it is. It starts with a devastating (and almost Hopkinsonian) monologue by a young Irish boy who has accidentally blown himself up and continues in the voice of his German neighbour, his depressed and grieving mother and, finally, his sister. Cleverly, movingly, it explores grief, love and the powerful, sometimes dangerous, intersection of private and public lives.

It's the first time that Hart has written about Ireland, the first time that she's taken on its history. It feels, I tell her, like a kind of coming together of all her concerns, a kind of coming home. Is that how it feels to her?

"It does," she says. "There's so much that has been shaken into a pattern that connects to Ireland and the philosophy that I had and that has crystallised in historical terms and in personal terms, so it has been a kind of gathering of many, many things... I'm very moved by the response, which has been really more than I could have dreamed of. It has been a balm to the soul, because it was so hard and so painful and it has taken me so long."

It has indeed taken "so long". Seven and a half years, compared to the brief outpouring of Damage. That care is apparent in every phrase, and also in the moral and historical vision that frames the book, a vision that's remarkably tough-minded. "I think," says Hart, "what exists profoundly in Irish psychology is the desire to make out of our history a mythology – which served magnificently until it was exploited. And out of that came absolution for what I regard as complete barbarism... You know this thing about truth and reconciliation. There is not a word of truth being spoken. They want reconciliation without the truth."

If Hart writes convincingly about grief and its aftermath, it's because she knows whereof she speaks. When she was six, her baby brother died. When she was 17, her nine-year-old sister Sheila, paralysed by meningitis when she was two, died, and then, six months later, her brother Owen, in an accident. Three siblings by 17 is beyond even a Lady Bracknell. Not just misfortune, but loss beyond all imagining. "I have never actually written about it in all these years," says Hart, "except elliptically in this book. The lessons that I learnt are really in all the books. It was an extraordinary thing to know that such things can be survived. What happened mathematically, to be very cold about it, in our family, was strange, but looking back on the history of mankind and going back to all the great literature and the Greeks, grief and loss is part of the human condition."

And if, as Sylvia Plath once wrote, dying is an art, so is surviving and it's one that Hart, like Plath's Lady Lazarus, does "exceptionally well". First, she moved to London. Then, fearing that her first love, acting, would bring her too close to the "scary stuff" she was trying to escape, she went into publishing and ended up on the board. And if she was ever tempted to sink into a morass of grief and despair, she would, as the nuns and her parents had trained her, pull herself together. "If I had let my parents down in that way," she says, "I would have been ashamed of myself."

It's perhaps not surprising to discover that this fierce, passionate, intensely moral creator of glittering, crystalline little novels was a good friend of another fierce, passionate, intensely moral etc novelist, Iris Murdoch. They share an obsession with the frailties of human beings, and their sexual conduct, as a vehicle for exploring what Murdoch called, in her novel of the name, "the nice and the good". They are, or in Murdoch's case were, both tough on themselves. Hart, in fact, left an earlier marriage to be with Saatchi and has never granted herself absolution. "Well," she says when I ask if she would be pleased to be described as good, "it would be so inaccurate."

Actually, it wouldn't. Mrs Maurice Saatchi, rich, happily married, blessed with two healthy grown-up children, bestselling novelist, patron of the arts, is, rather irritatingly, certainly nice. She's also, I think, good.

'The Truth About Love' is published by Virago