Baby Mama is causing issues!

Hello everyone,
Me and my bf have been together for some months. I’ve known him for a few years now and we made it official. Things are going good but his child’s mother is truly causing problems. I already know that his son is priority and I will never compete with that or try to interfere with anything. She is just young and very immature mentally. I could tell by the way she talks to him in the phone when I am around. She somewhat bullies him and uses his child against him at times. I remember a time that she called and he answered when I was right here and he was talking to his son and here she comes saying smart ish to him. She said “look baby your dada be over a work kissing those nasty heffa” she then goes “look baby say yuck to dada” smh like what’s the reason why are you trying to provoke a problem with him. I am laying there next to him just disgusted. Another time he was out shopping for his son for his birthday and she calls with a whole attitude. She fusses and says “I bet you out there with some bi***” like huh. I wasn’t even around him he is the one that told me about they conversation that day. I noticed when I am around him it’s always something that comes up and out time ends up being cut short. It’s either she want watching the child and he ate something wrong or the child gets sick or she just finds something to argue about. It’s irking me. When they argue his mood changes and it impacts our phone conversations. He doesn’t want to talk. I’m understanding I allow him to vent when he needs to. When he doesn’t want to talk because he is irritated I understand. I put my issues I am going through mentally to cater to him from the issues with the baby mom.
He gets off the phone when she calls and never calls me back. I use to get mad but I don’t even care to anymore. If he calls back he does if not he just doesn’t. I’m over that. She doesn’t even know about me and that’s fine. I can already tell that if she knew she would have a fit about it. She already gets in her feelings and keeps his son away just because she feels like it. She sometimes drops him off to him when it’s not even his weekend and doesn’t give him heads up. I went into this relationship not even knowing there was drama. He had this child when we were just cool. He claims they were just “messing around” and she ended up pregnant. I can only go off of his word. I’m a chill and peaceful type of woman. I am in my 30s and I don’t like problems or chaos. He is a gray guy but his baby mothers is driving me absolute nuts. I can’t just have a peaceful weekend with him without her calling talking mess. I had a Valentine’s Day getaway set up but I know if she FaceTime him and she sees he is not on his home in bed she will start fussing. Please help. Sorry for the long rant.