My brother is my mad at me(need advice)

Yesterday my brother group messaged​ me with mother of his children saying was informed by my nephew that mother is pregnant. They haven't been together for 2 years and she waited for him. I told him he had no right be angry. I say to her it should came from you not my nephew . He goes on to tell me he going call CPS . I ask why when she takes great care of your son's. He tell me that doesn't play that having another nigga around his children. I say to him that she is engaged it's not random man and grow up. It is unrealistic expectations for either one or them to say they don't want another woman or man around they kids . There should be rules but to say that is to say I don't want another woman/nigga around my kids, is to they can't ever be with anyone else. He says she stupid guy she engaged to is probably cheating on her 9/10. I tell him they are happy and he didn't want her and had plenty of women so man up. He goes off on me tells me I taking her side and that I don't care. Than tells me I'm salty and our little sister was right I wouldn't understand . I told him my job is to tell you the truth and protect my nephew's not your ego. Apparently now I'm a bitch