Talking to the same girl

Hey everyone! I need advice. In September of last year I found out my boyfriend was trying to get with another girl after I told him I wouldn't have sex with him when I was a virgin. I decided to stay since him and the girl never actually did anything. We had arguments and he said he wouldn't talk to that girl anymore but I just found out that he has been talking to her again and she is calling me a bitch without him defending me. He's giving her his passwords to different social medias and she is getting on them freely. Should I breakup with him? Does anyone have any advice that could help me?