Tell him it's not going to happen and that he needs to drop it.
It's pretty simple, if you don't want to it then that is the absolute end of the conversation. It's your body, and the only person who gets a vote on what goes in where is you. You have done every single thing possible to try and mediate this issue and, well, none of them have worked, so he needs to let it go. If this bothers him, then he needs to talk to a therapist or a professional. That simple.