Evermore - By Sara Holland

Jules Ember was raised hearing legends of the ancient magic of the wicked Alchemist and the good Sorceress. But she has just learned the truth: She is the Alchemist, and Caro—a woman who single-handedly murdered the Queen and Jules’s first love, Roan, in cold blood—is the Sorceress.
The whole kingdom believes that Jules is responsible for the murders, and a hefty bounty has been placed on her head. And Caro is intent on destroying Jules, who stole her heart twelve lifetimes ago. Now Jules must piece together the stories of her past lives to save the person who has captured her heart in this one.