Having trouble with my boyfriends family.

Abbie
So me and my boyfriend met when I was about 2 months pregnant. He's not the father of my child, her biological father is in jail for putting his hands on me.. He didn't hit me but our relationship was toxic, I was yelling one day telling him to leave and he lost it and grabbed me and threw me on the bed with his hand over my mouth, my mother walked in and called the cops. However that's not why he's still there. I won't get into that but he could be looking at 2-5 years. Not only am I dealing with her biological fathers family pissed because I won't be giving her his last name, she'll have mine, but I'm alos dealing with my boyfriends family not accepting me. I feel like an outcast, they barely speak and everytime we mention something about our little girl they get frigid and insist on reminding me that she's not his. She is his though, she may not be his blood but he's stepped up and wants to raise her as his own. I don't understand why his family just can't accept that and be happy for him. Any advice? I've just been avoiding them since I have a real problem holding my tongue.