Welcome Skeptic,
I don't know how old you guys are, but I'd say this is the beginning of one of the most turmulous times in his life. If he wants to keep you, he'll have to stand up to his mom and everyone fromhis childhood for the first time in his life. If he choses to please his mom then he's going to ask you to lay low/move out for the week his mom is in town. He has to make a choice, and it's not about you, it's about him stepping up to the plate and growing up. It's hard to do. I would cut him some slack and give him a little time, but don't let him let things continue the way they are for too long. Good luck.
GG