don't know anymore

Hey girls! I know it's New Years but I really need advise. So we are having a party and at my house and my boyfriend and his brother are coming. We are all good friends including with my mom. The brother is highly annoying and loud and my mom always has to entertain him. I told my boyfriend he could come over early but not the brother. My boyfriend got all pissed and said that it was all my fault he had to lie to his twin brother. I feel like the brother is old enough (18) to understand that he doesn't need to come over because of the fact that just because my boyfriend does he doesn't need to also. It irritates me that just because my boyfriend can come there is a big issue. I'm so mad I can't even describe how I feel. I told my boyfriend he didn't have to lie to his brother he could simply say "hey I'm going to Lauren's house now I'll see ou later" and if the one other had a problem with it he could just say "no no one is ready yet" I don't see wha the big issue is about him waiting till everyone is ready BECAUSE HE ISNT MY BOYFRIEND. My mom doesn't want to deal with him right now because of how loud he is. This might sound stupid or petty but I dealt with this last ear (if my boyfriend comes over so does the brother) we are all 18 and I think it's just immature for people to be butt hurt. Advice ?