The Surviving Girls by Katee Robert

Twelve years ago, Lei Zhang and her friend Emma Nilsson miraculously lived through the notorious Sorority Row Murders that left twenty-one of their sisters dead. Still wrestling with the trauma but finally out of the limelight, Lei and Emma are now devoted to helping other victims find closure. But most disturbing for Lei—beyond the gut-wrenching survivor guilt—is that the killer was her boyfriend. He’s behind bars, but she’ll never lower her guard again.
When a copycat killer targets Lei and Emma, FBI Agent Dante Young is put in charge of anticipating the sociopath’s every move. But what he doesn’t expect is his immediate and overpowering attraction to Lei. The closer they get to each other, the more desperate and terrifying the questions become: Who wants to finish what the killer started—and why?
Now Agent Young vows to protect Lei at all costs. If they have any chance of a future together, first they have to stay alive…