Lock on the door is your best option, don't leave anything out in the open.
It sucks, I know from personal experience I have been there. But it will save you so much greif just keeping it out of sight, out of mind for him.
I would get a lock for the knob, if that isn't enough put a pad lock on as well. Hopefully the guy, seeing the lock, will give himself a reality check that it had to come to this.
Edit: didn't read this page, apparently a lot of Lock suggestions already, oh well add this one to the pile
Another option is instead of letting him get away with it, every single time it happens you bring it up. And not in a nice way. If he confronts you physically then you should be moving out immediately because this guy is unstable.