Ripple Effect by Kathleen King

Ten years ago, seven college friends stood in judgment of their peer, and their plan for revenge went horribly wrong. They vowed to keep the secret…and the guilt of it…between them. This decision has affected all of them, but most of all Lexi Cooper. As the latest note is slid under her door one evening, she crumples to the floor, both afraid for what will happen and resigned to it, because she knows whatever it is, she deserves it.