Nadia Knows Best by Jill Mansell

Nadia has been dating her childhood best friend (Laurie) for years, and even though things are a little rough (with Laurie's new modeling career taking off), Nadia doesn't let temptation in the form a night stranded in a snow storm with a stranger make her cheat on the love of her life...Too bad Nadia didn't know that Laurie was already planning on dumping her.

18 months later and Nadia has pulled her life back together. She's now working for the man she spent the snow storm with, and is even starting to consider dating again...then Laurie shows back up and declares his undying love for Nadia and explains his regret at dumping her.  Now Nadia is torn between her new boss (Jay), and her old love.
This story is also filled with characters in Nadia's family:  her selfish artistic artist Clare, her adorable 13 year old half-sister Tilly, her father, and her captivating grandmother (all of whom she lives with), and her crazy whirling dervish of a mother.  Each character gets his or her own story, and some of the stories are stronger than others.  Nadia is a likable character, and the humor and heart in this book propel the narrative.  I pretty much wanted to strangle Clare throughout the entire book, and Tilly's story broke my heart (in a good way).  I look forward to reading more of Mansell's work.