Creep

From Amazon: Dr. Sheila Tao is a professor of psychology. An expert in human behavior. And when she began an affair with sexy, charming graduate student Ethan Wolfe, she knew she was playing with fire. Consumed by lust when they were together, riddled with guilt when they weren’t, she knows the three-month fling with her teaching assistant has to end. After all, she’s finally engaged to a kind and loving investment banker who adores her, and she’s taking control of her life. But when she attempts to end the affair, Ethan Wolfe won’t let her walk away.

. . . no one else can. Ethan has plans for Sheila, plans that involve posting a sex video that would surely get her fired and destroy her prestigious career. Plans to make her pay for rejecting him. And as she attempts to counter his every threatening move without her colleagues or her fiancé discovering her most intimate secrets, a shattering crime rocks Puget Sound State University: a female student, a star athlete, is found stabbed to death. Someone is raising the stakes of violence, sex, and blackmail . . . and before she knows it, Sheila is caught in a terrifying cat-and-mouse game with the lover she couldn’t resist—who is now the monster who won’t let her go.