The Twilight Zone Episode 2.01 Meet in the Middle

A socially awkward single man named Phil hears the voice of a woman in his head. His therapist suggests he is suffering from dissociative identity disorder.

However, being able to talk to the voice, Phil decides to meet up with the putative woman in a location halfway between his city and hers. The voice says she was unable to attend as she was abducted and she gives Phil directions to the isolated house she is kept at and a description of her abductor. Phil arrives and pummels another man to death in front of that man's young daughter and he is arrested at the scene. He believes his therapist was right about him being insane until the voice comes back and thanks him, revealing that she is the wife of the dead man, that she never lied to Phil, he just believed what he wanted to, to the point of being prepared to murder, and that by killing her husband, Phil has been the "escape hatch" for her unhappy marriage. Phil starts to go mad as the police car drives off.