Dead Wrong by Alexander C. Eberhart

Tobias Greene is dead. Or, at least, he was dead, before his ex-boyfriend woke him with news of his missing sister.

I wasn’t supposed to be here. Death should have been the end for me. A quiet erasure of all the terrible things I’d done in the almost thirty years of my first life. But then I was awake, and those memories came flooding back in, destroying the peace that had saved me in the crushing dark. To make matters worse, Bastien, the man I loved—and lost—was the one who tore me from Death’s icy grip. I couldn’t remember how things ended between us, but judging by the contempt in his eyes, I would guess it wasn’t pleasant.
Lynette was missing. My twin—my better half—vanished the night before she was to succeed our mother as Head of the Magi Council. I was the last one to be seen with her. Then I was murdered. Now, I had to piece together those moments leading up to my death if we were to have any chance of saving Lynette.
I wanted to forget the man I was in my first life. But with every step closer to Lynette, my past stalked ever closer. The hearts I’d broken. The lives I’d ruined. The men I’d left behind.

I thought I knew who I was, but I was wrong.
DEAD WRONG.