I don't know what went wrong...

Amanda • Pregnant with my 3rd and mommy to an amazing 10 year old girl and almost 3 year old boy❤️
My SO has been amazing throughout my pregnancy... Then the last week everything changed. He became distant, stopped coming to bed, started accusing me of things I'd never do (cheat, lie, steal...) and his brother just egged him on. Today my SO pointed to my baby bump and said "how do I know that's even mine?!" And I was so hurt that I slapped him across the face. I'm so ashamed but I was so hurt because I'd never consider it. We already had to have a paternity test done because my SO is disabled but I didn't care because I have nothing to hide. Just him even making the accusation hurt so bad... Now  aty dads house 2 hours away. I didn't know what else to do because I couldn't handle a note verbal abuse. I love and miss him and I can't stop crying. We haven't talked all night... I don't even know where we stand. He chose to believe his brother over anything I had to say... I just don't know what to do. I'm 38+3 and I want our family so bad but what do I do if he just doesn't want it anymore?  So afraid to raise another baby by myself.... Any advice would help