The needle's eye - Margaret Drabble

Simon Camish, an embittered, diffident lawyer in a loveless marriage, would not have particularly noticed Rose Vassiliou had he not been asked to drive her home one night after a dinner party. Yet at one time she had been notorious-her name constantly in the news.
Now, separated from her Greek husband, she lives alone with her three children. Despite all the efforts and sneers of her friends, she refuses to move from her slum house in a decaying neighborhood to which she has become attached. Gradually, Simon becomes aware that Rose is a woman of remarkable integrity and courage. He is drawn into her affairs when her husband takes legal action to reopen the question of custody of the children-a scheme for getting his wife back. And, while the precise nature of their ties eludes him, Simon comes to realize that Rose and her Greek ex-husband are forever and inextricably bound to each other.