The only way to ensure that he doesn't touch any of your stuff is to lock it up or remove it from your home. Can you box it up and store it somewhere overnight, such as your car, garage, your job, or a friend's apartment? If you want to tape up your fridge, don't be subtle. Seal it in such a way that it would be obvious if it was messed with, like tamper proof tape. Tape it up, take a photo with your phone, and take the remainder of the roll of tamper proof tape with you when you go.

I kind of want to know how he is twisted in an unhygienic way, and a kinda really DON'T want to know! Good luck!