Your Roots Are Showing by Elise Chidley.
Found this book at RWA (a Rita nominee) and was glad I did. It's sweet and charming and pulled me right in.
Lizzie Buckley has a life many women dream of - a gorgeous husband, a beautiful home and darling (when they're not fighting) three-year-old twins. But ever since the birth of her children, she's had a fantasy about locking herself in her bedroom for twenty-four hours with a good book and a box of chocolates. Unfortunately, her husband James doesn't understand her feelings. And when Lizzie unburdens herself in a flaming email to her sister Janie, then hits send at the wrong moment and accidentally shoots it off to James instead, her fairytale life gets a big dose of reality. With the word "divorce" ringing in her ears, Lizzie finds herself moving out and embarking on a totally different life - working hard to reinvent herself as a runner, a gardener, and a writer of children's books. But despite transforming her body, her neglected career, and her libido (courtesy of the local landscape gardener), Lizzie can't get over her soon-to-be ex. As Lizzie discovers, sometimes the fairytale ending is just the beginning of the real story.