Sweet Revenge, Slimmer Me

Lena Beckett was the invisible one. The girl in the corner with the snacks, the sweatpants, and a husband who told her she should be 'grateful he stayed.'That is. until he didn't. Betrayed by her picture-perfect husband and the size-zero mistress, Lena's world crumbles. But just when she's about to drown in self-pity and cookie crumbs, Lena finds an unlikely ally in a mysterious woman who offers her a lifeline - a chance to reinvent herself and exact delicious revenge.
As the pounds melt away and her confidence soars, Lena builds a dazzling new life complete with career success and the attention of a man who sees her true worth. But she hasn't forgotten those who wronged her. With her benefactress's guidance, Lena crafts the perfect revenge-one that will leave her ex-husband and his mistress wishing they'd never crossed her.