What do i do??

Im in a serious relationship right now. So we broke up in feb because his female friend told him to. And theyre still super close now, see each other nearly every day (we are in college) for class and to study together. They message all the time, post on each others timelines, etc etc. do you think this is disrespectful and rude? I have made it clear i hate her for what she has done and she makes me uncomfortable. He hasnt done anything. Should i break up with him? I feel like boyfriends shouldnt do this, especially with warnings. I feel like it should be common sense anyway. Thanks :)