A Demon's Desire by Lizzy Ford.
"Emma crossed paths with a black witch in an ill-fated love triangle that ended in Emma fleeing and the death of the man they both loved. Two years later, the witch is revenge and strikes against Emma’s family. Emma turns to the only person who can help her: a man rumored to be half-demon with the power to control the shadows. Tristan agrees to help her lift the curse on her family but isn’t prepared for what he finds hidden in Emma’s secrets."