I think I need to tell my roommate to back off.
Why do you want him to back off?
He's been too attached to me recently and it makes me feel uncomfortable
Maybe you should find a way to talk to him without hurting his feelings. It would be rude to tell them to just back off.
I'm going to slap him if he touches me. That'll show him.
I don't think a physical confrontation will fix anything here. Just tell your friend you need some space and if they care about you, then they will oblige.