It would irritate the crap out of me as well to have my in laws dropping by whenever they choose together with the obsessive relationship that he has with them. It's one thing being a good and caring child but another when the relationship overtakes your own. Obviously he is aware of how you feel so he needs to accommodate your feelings as well as you are just as important as his parents. It shouldn't become a me versus them scenario as this will only breed tension and affect your own personal relationship but he needs to be aware of how his behavior is upsetting you and compromise accordingly. Perhaps a therapist to act as a mediator would help so that you can reach a happy win/win situation might help. Whatever it is you need to address it rather than running to the bedroom each time they arrive and letting this stress you out. Good luck x