My boyfriends ex freaked out that I went with him to drop his daughter off: Advice?

Basically, I’ve started seeing a bloke. We get along like no other. It feels like we are made for each other. But he has a child to his baby mummy. There were together for a while. She cheated on him and kinda abused him. They have split custody of a little girl who is 3. He and I have weekends where I go to his, and he comes to mine ( baby mummy works through the week), so it works out well. I’ve met the little girl this week. ( we have been seeing each other for about eight months) and everything was great we are great little girl is so well behaved. Now. The day after, I came over and met a baby girl. Baby mummy rocked up and starting screaming and swearing, and she tried to take a swing at me for being there and actually hit my boyfriend. The little girl was in the car. Baby mummy said she was taking her and not giving her back. Apparently, he can’t see his little girl until they go to court, apparently because he has a new woman in his life. It was brutal, really bad. He also showed me the very abuse messages he gets off her, plus logging into his Facebook and blocking me, spam calling him, not letting him have his daughter if it’s his turn to have her. And he doesn’t even get angry at me. I don’t really get it ( I would blow up). He doesn’t. They have been together for about two years. I just guess I’m asking for advice. I don’t have kids and can’t have them, but I’m really good with the young girl. I just don’t know what to do. I feel so bad like it’s my fault and my boyfriend is quite upset. Oh, mind you. She has a fiancé.

Oh man, that is tough. Stop going with him for now until he goes to court.