Hysteria by Megan Miranda (author)

Mallory’s boyfriend was stabbed. He bled to death in her kitchen. Mallory was the one who did it – but she can’t remember that night. She only remembers the fear… When Mallory’s parents send her away to boarding school, she thinks perhaps she can escape the gossip and the threats. But someone – or something – has followed her. The hand that touches her shoulder when she’s drifting off to sleep. A voice whispering her name. Meanwhile, her secret has escaped. Everyone knows what happened. So when a pupil is found dead, Mallory’s name is on their lips. Her past can never be erased, and it can never be forgotten. A killer is on the loose – but is it her?