Losing Faith by Denise Jaden
A terrible secret. A terrible fate.
When Brie's sister, Faith, dies suddenly, Brie's world falls apart. As she goes through the bizarre and devastating process of mourning the sister she never understood and barely even liked, everything in her life seems to spiral farther and farther off course. Her parents are a mess, her friends don't know how to treat her, and her perfect boyfriend suddenly seems anything but.
As Brie settles into her new normal, she encounters more questions than closure: Certain facts about the way Faith died just don't line up. Brie soon uncovers a dark and twisted secret about Faith's final night...a secret that puts her own life in danger.
I'm loving the sound of this one and how awesome is the cover? It's published September 2010 (US)