Well if he doesn't respond to the Notice to Quit then you can file the eviction paperwork with the courts. After you serve the notice he might be more willing to discuss things like an adult. It may be better to wait until he gets the notice to work out some sort of agreement? This is where hiring a lawyer would be crucial.

Again sorry you're in this situation. If I was in your shoes I would be seeing red at this point. Don't stoop to his level though. If you do something like move his stuff it can really mess up the eviction process. I'd be more worried about a judge ruling against me than a civil suit.