What book by Diana Palmer is this..?

What I can remember about it is its about a girl whose bestfriend is sort of using her to cook for all her parties and stuff. And she looses a lot of weight and wears baggy clothing. She gets drunk one day at one of the parties and her best friend's brother who she was in love with or something takes her upstairs and they make out. The next day he badmouths her because he is frustrated and she hears and she leaves sad and goes to work somewhere. Thats all I can remember please help :$