The Escort (1997)

Suzanne (Shauna O'Brien) is a psycho escort who becomes the roommate of a young couple, Debra and Shane Gray (Landon Hall, Scott Coppola). It turns out that Suzanne had been committed to a mental hospital many years before when she flipped out because her closeted lesbian sister, who was secretly in love with Debra, committed suicide after Debra rejected her romantic advances and carelessly outed her in high school.