Flawless (Pretty Little Liars #2) by Sara Shepard
Spencer stole her sister's boyfriend. Aria is brokenhearted over her English teacher. Emily likes her new friend Maya . . . as much more than a friend. Hanna's obsession with looking flawless is making her sick. And their most horrible secret yet is so scandalous that the truth would ruin them forever.
And why shouldn't I tell? They deserve to lose it all. With every crumpled note, wicked IM, and vindictive text message I send, I'll be taking these pretty little liars down. Trust me, I've got enough dirt to bury them alive.