Growing up, Marian Keyes never thought of herself as a writer - and came to her profession almost by accident in the early 1990s.    She has since become one of Ireland’s most successful novelists - with over 35 million copies of her thirteen works sold to date. Keyes is beloved to her readers for her wit, her conversational prose style, and for the unflinching honesty with which she approaches her subjects, which include depression, infidelity domestic abuse and the glass ceiling.    Here, she talks to Laura Powell about love, marriage, her own journey through depression - and her latest novel, The Break.