If I was in this situation, I'd probably have to settle things manly with the guy. People are probably going to call me out for being an internet tough guy for this but honestly, that's just how we deal with things from where I am. Not the best idea tbh as there are things related to the law, but if someone's touching up your girlfriend then it's pretty obvious that the person needs to be taught a lesson not to do it. You could file a restraint order which is a better alternative but I think I'd solve it the way I would. He's going to kill himself? lol, natural selection- nah, but he's obviously cognitively unstable and needs to seek help as soon as possible. You really need to block that guy off from everything to solve the problem or just contact the authorities if that's what you want to do
Deus, I see where you are coming from. Sometimes in life you just need to leave forgeted up situations because they're wasting precious time. I understand your point of view but I don't know if that would be the best thing to do because you don't know how good OP's relationship really is, the two might be extremely committed to each other. But yeah, your girl should never be going to another boy's house alone with that boy, that's a no no