Not sure, how to get it to officially stop. It's perhaps, so ingrained in his every ounce of his fiber, that stopping him, aka, changing him, it highly unlikely.

The only thing, that can change, is your reaction to it. Learning to detach, whether that be to emotionally step away or physically step away, even to another room, is a start.

Do you have any relatives, or friends, that you can start spending more time, with? Away from him?