By The Time You Read This, I'll Be Dead by Julie Anne Peters

Book trailer produced by Rose Curley.

Daelyns been the victim of bullying throughout her life and now shes simply counting down the days until she can commit her final act on Earth. Its destiny that she finds a Web site to help her in her quest. She has the motive, the means, and the determination. Then she meets this boy, Santana, who makes her examine her choice of death over life. But is he too late to save her? And is she too damaged to save him?

http://julieannepeters.com/files/Exce...
(From the YouTube description)