What should I do about this situation?

My boyfriend of 5 years left me Monday for his friend's married aunt. She is living with her husband and 3 kids. Her husband has no clue at all. I am 9 months pregnant, and our first child is about to turn 4 in 2 months. You can imagine how hurt I was. He spends no time with our son, he would rather spend his days with his friends, smoking weed. I couldn't even get in his car because it smelled horrible. So he is gone, I don't know if he is planning on trying to see the baby after she is born, but I know his family is. I don't want his family around me or the children, for the simple fact that they just laughed when he did what he did Monday (I was not a bad girlfriend, I was just like a wife, and I don't bother his family), they have not offered any kind words at all through this, and they are claiming that it's not his child. He has never said that to me or made a claim like that, he always pretended or put on that he loved this baby like she was God. He will not be allowed in the hospital or to sign the birth certificate because my doctors have noted where he has emotionally and verbally abused me, and they view him as a stress factor. The question is am I wrong to not want his family involved at all, period? I know that it is in a way, but I'm tired of being hurt by this family, when it bothers me, it will bother my children, because they sense tension. I just want to do what's best for them. Advice please, and please no rude remarks, I am going through enough as it is.