Cursed Heart by Sarah Bailey

Attacked in the dark. A murderous psychopath. A shifter’s curse is so much more than turning at the full moon.
A night out turns into a full blown nightmare. If Rex, a feline shifter, hadn’t come along, Izzy would’ve been done for. When she discovers she’s becoming a shifter herself, her life crumbles before her eyes. Being bitten is the least of her problems. Rex doesn’t know what she’ll turn into and the person who attacked her is murdering girls. Izzy is the only one they left alive.
Come the full moon, Izzy turns to Rex for help when she wakes up in a pool of blood, unable to recall what happened. Soon she finds herself mixed up with shifters, witches and fairy magic. Despite being drawn to Rex, she’s reluctant to get close to her fellow shifter. Not when she’s got secrets of her own.
Will they find out who’s behind the murders? Or will her attacker come back to finish the job?