Your boundaries are about you and your space wherever you are. They go with you (like your shadow). His stuff in your space is his stuff. If you are there then it's still your space irrespective of his stuff. His stuff represents him but isn't him. If his stuff is used as an excuse to invade your boundary then for the time you are there it's your space. When he is its his and your stuff is just your stuff.
So if your time in the house or the car or at your mum's then that's your space. Access to your car should stop, it's your car so have an alarm on it and set it. Changing keys is tough, add an immobiliser if necessary so he can't use it or a crook lock device.
This is where you need an L to tell you the law in your jurisdiction, I have given you my opinion on the emotional boundary and an L can tell you about the legal one.
Touching you with out your consent is serious and explain to your L this is happening.
Where I am this is considered assault, I know I had victim support and police help. If it's sexual as well (mine was) then it's sexual assault. It's very serious and I am concerned for you.
This seems to be in your R and you haven mentioned any childhood issues in response to my questions so I think good boundaries may help.
Hugs
V
Freedom is just another word for nothing left to loose. V 64, WAW