Bad Blood by Cate Corvin

Forgiveness is divine weak. A woman who desires revenge should dig two five graves. An eye for an eye makes the world blind is incredibly satisfying.
Will and Sura made me believe I was one of them, only to betray me in the worst way. With a second chance to prove I deserve to be in Libra Academy, I’m going to serve the pain back in spades. I’ll destroy Will’s pride and unearth Sura’s secrets, annihilate their family honor… and stab their accomplices in the back for good measure. If they die, they die, but I’ll be the last one laughing.
My hate for the Shadowed World has been turned inside out, in no small part because of my alliance with Càel, a knight with an inexplicable desire for me. Who’d have thought a vampire would be the one to defend me from my own kind?
With my unlikely ally at my side, I’ll have my revenge on the ones who tried to ruin me. No punishment is too harsh for them. But our feud isn’t the only one, and there are others who want me dead and gone.
Unfortunately for them, I’ve got vengeance to spare.