Unless your boyfriend plans on being abstinent until marriage with not just you, but /anyone/ he potentially dates afterwards, he is going to clash with his controlling parents on this and the problem will not just go away on its own without addressing it. He needs to decide now if he is going to risk his relationship with you by postponing the inevitable drawing of boundaries with his parents, or if he's going to set the ground rules with them now and you can support him emotionally while he seeks therapy and learns how to remove himself and you from that situation and those people. This is more his issue than yours, and it's entirely up to him whether or not he wants to deal with it now or if he wants to deal with it the next time he has sex with someone. The most you can do is help him realize that this isn't something that will get fixed by bargaining with his parents, but by seeking help and becoming self-sufficient. It's hard getting to that point, I've been there, but once he gets away from them and can support himself so they don't have the power to "ruin everything good", he's going to never look back and he'll breathe easy for the first time in his life, I bet.