there must be more to this story than movie shows(spoilers)
I found it hard to feel sorry for or forgive this kid who seemed to come from a good home, yet got drunk out of his mind and viciously attacked and killed an injured adult man who had done nothing more to him than nicely ask him and the other kids to move their party downstairs. His excuse was that he had been laughed at by other kids when he hadn't stood up to a bully. This man was not a bully,he was already injured, and the other kids didn't even see the boy's cowardly attack on the man.
There was obviously something radically wrong with this boy, but it wasn't explained satisfactorily in this movie, so that I could sympathise with the victim's wife being so forgiving. There was probably more to the disturbed boy's story in real life, but it wasn't in the movie.