Lethal Seduction

High-school senior Mark has never minded his overprotective widowed mother Tanya and is a good son to her as he prepares to go off to Princeton in the fall. One day, he goes to a hardware store where he meets attractive middle-aged widow Carissa, who convinces him to come fix the shower at her house. She seduces him and they have sex. When he comes under the spell of this rapacious, manipulative woman, he lands between two strong, unreasonable women--one of whom is insane. After learning that Carissa's ex-husband was found dead at her house, Tanya visits Carissa to make amends but Carissa rejects her and threatens to convince Mark to do whatever she wants, including cutting Tanya out of his life. —Wiki