I just…I feel bad for Marty. His dad was such an abusive jerk, and then he’s finally free of him but he literally starts hallucinating every bully in his life as having his father’s face.

That doesn’t at all excuse his treatment of Natalie toward the end, poor girl (which I think he understood on some level, given he started hallucinating himself with his father’s face). But he definitely needed therapy and help and I doubt he’ll get it in prison.