Most of us know couples like Catherine and Francois Kelly. After 25 years of marriage, and four sons, Francois, a French business executive of Irish descent, leaves Catherine, a successful novelist, to live with his mistress. For a quarter of a century, Catherine had put up with her husband's escapades in the belief that he would always return to her - The First Wife. Now, at the age of 50, she is "in mourning, in mourning for my husband who is still alive".
The First Wife is a scarcely veiled autobiographical novel by Francoise Chandernagor, and its wrenching tale of her own recent divorce has become what the French call a phenomene de societe. "If every woman whose husband dumped her after 30 years of marriage buys the book, it will be a huge success!" the writer Francoise Giroud predicted - and that is what happened. In 3 1/2 months, more than 230,000 copies have been sold and the book remains at the top of the best-seller list.
French literature abounds with lyric accounts of illicit affairs as experienced by lovers, but it has rarely taken the point of view of the wronged spouse. Ms Chandernagor has also pioneered a new genre in revenge. For her ex-husband's second wife, she writes, her soulbaring book will be "an invisible presence that is felt everywhere, a poison in the air she breathes".
The author receives 30 letters a week from women who identify with her narrator. "I opened your book one morning," a 53 year-old divorcee wrote to her. "I closed it at 20 minutes past midnight. In every word, on every page, I found my own story. Twenty-four years of my life in fast motion. Thanks to your words, I have exorcised this pain inside me. My heart is at last at peace. Thank you, thank you, a thousand times thank you." I've heard The First Wife discussed at every French social occasion I've attended this summer. At a country luncheon last weekend, the hostess, the wife of a retired company director, whispered out of his range of hearing that her husband wouldn't let her read The First Wife because "he was afraid I'd be furious with him". The husband in the novel was an incredible cad, a guest remarked - but so realistic.
Long before Hillary Clinton, French politicians' wives were notoriously long-suffering. Confronted with the news that her husband had raised an illegitimate daughter with his mistress, Danielle Mitterrand said she'd known all along and sighed, "Mazarine is such a pretty name!" But the husband in Ms Chandernagor's novel breaks all records for boorishness. Early in their marriage, he tells his wife that he brought his mistress home in her absence. "She thought our flat was messy - especially our bedroom, and the bed badly made." At their country home in Provence, Francois Kelly keeps an alphabetically listed drawer of love letters, plane tickets and tourist pamphlets - starting with A for Adeline, and ending with Y for Yolaine. From time to time he pulls a file out to show Catherine.
At first, Catherine Kelly pays no attention to the lavender-blue love letters that her husband leaves lying around their flat. "The lady made so many spelling mistakes that I didn't feel threatened," she explains. But on their 25th weddinganniversary, in an expensive Paris restaurant, he holds his hands in front of her face and taunts her with the claim that he hasn't worn his wedding band for the past year. Are French husbands more cruel, more unfaithful than others? The French have always been so superior about sex, looking down on others as naive country-bumpkins with ridiculous hang-ups over fidelity and guilt. According to the Francoscopie, a source book on French society, 43 per cent of French men and 35 per cent of French women believe that love does not require fidelity. After the second World War, the life-long relationship of the existentialist philosopher Jean-Paul Sartre and the writer Simone de Beauvoir - who told one another about their affairs - was often held up as a model. The rebels of May 1968 emphasised sexual freedom and equated fidelity with property and possession.
Ms Chandernagor's book is the first with wide appeal to challenge the idea of "open" marriage. It has already changed the tone of French women's magazines. Jealousy is a healthy emotion and an integral part of love, the psychologists' columns now comment, advising female readers not to tolerate serial infidelity. For Ms Chandernagor, the statistical banality of divorce - which ends one in three French marriages - in no way lessens its pain. "Divorce is made to destroy, tear out, pulverise," she writes. "The worst thing is that like the butcher's hatchet, whatever it cuts it also infects. And this gangrenecontaminates everything: friends, parents, children."