Can someone help ... -advice needed

So my boy friend who I love very much has a 5 month old from a different woman (before we met) and he tried doing the right thing to be with her but they were never together and he is not happy with her . She holds their daughter over his head at anything he does . He has came out to her about us being together but she has called me names , over crossed boundaries , and has made me feel very uncomfortable. I ask him to stop but he does say “I can’t piss baby momma off” . Now today she called him and asked if he could put the speakers in her new car tomorrow and he didn’t tell me until I got back to my house and I felt upset because I felt like I wasn’t included on when they make plans , and it’s not necessarily that I’m jealous but I feel like we should all be working together and I wish Emmy boyfriend would just stick up to her .... advice please 😣