My bf attacked my best friend! Please Help!?

Ok we are all in 7th grade. I have been going out with my bf for 3 weeks now and he is wayyyyy different from normal guys. he watched chick flicks, has a lot of female friends, doesnt care about looks, and is super sweet. Well i have had a best friend since 1st grade and we r like sisters. Well every day at lunch my bf sits to my left and my bff sits to my right and there are a bunch of other friends but aren't a part of this question. Well, today my bf wanted to tell me something important that only i could know about. And he said i cant tell my bff. So i said ok fine. So my bff wanted to know wat it was so she was like "She will just tell me anyway, you do know that," And then it was time for us to leave lunch so we started walking and my bf found one of his friends. SO me and my bff were walkin to cl and then my bf came back beside me. And he told me he was going to tell me the important thing right now. So i said ok. And then my bff was like "Tell me tell me tell me!" and then my bf shoved her and then she slapped him and then so on and so on. then a teacher saw him shove her and he got yelled at. But they are always yelling at eachother and he maily starts it by saying something rude about her when she isnt doing anything. She hates him caz he is really annoying to everybody, thats just who he is, he annoys everyone. And he hates her because he thinks she is a bad influence on me....idk? But please help me I dont know what to do. My bff now has a ton of bruises and she REALLY hates him even more then she did. They are always doing this and i dont know how to stop it or to make them be nice to eachother. I told them to have a fresh start and then my bf just antagonizes again. He is always doing this and its mainly his fault.How do i stop their fighting? Help!