Dementia (1999)

Over the edge is just the beginning. Katherine, a beautiful heiress recovering from a mental breakdown and her nurse, Luisa, develop a special friendship as they open up to one another. But as their closeness--and attraction--grows, Luisa's sadistic ex-husband Sonny re-enters her life with a scheme to get back at Luisa, and take over Katherine's fortune. As his manipulative plan unfolds, a lurid tale of seduction is exposed that breaks all the rules, and ends...in murder.