Watermelon by Marian Keyes

Claire has everything she ever wanted: a husband she adores, a great apartment, a good job. Then, on the day she gives birth to their first baby, James informs her that he's leaving her. Claire is left with a newborn daughter, a broken heart, and a postpartum body that she can hardly bear to look at.

She decides to go home to Dublin. And there, sheltered by the love of a quirky family, she gets better. So much so, in fact, that when James slithers back into her life, he's in for a bit of a surprise.