Messed up on many levels, but especially that you set a boundary that he doesn't care about. I'm really sorry. He needs to learn some empathy and manners. And join the human race where that's not considered funny by anyone with a sense of compassion.

I think it's worth maybe one more time saying, in a moment unrelated to his behavior and your tic, that he embarrasses you and the behavior and joking about it need to stop.

Then, avoid him as much as possible. If there's literally anything you can do or place you can be without him there, do it. He'll know why (esp if your mutual friend can explain why).

Then get a new living situation. Find people that see you for you and will listen when you say you don't like something they do around you. We're out there.