That sounds like a dangerous situation for your friend. Can he stay somewhere else for a while? If the other person is making threats, it sounds like getting away would be a top consideration. The other person sounds abusive and not safe. I'm sure during covid that could be more complicated. Does the other person have some kind of leverage against your friend? It's not just women that are abused--men are too. Does your friend have a roomate, or a lawyer? Or maybe a friend who is bigger and intimidating to the guy that's bothering him.