My boyfriend's family (mostly his younger sister) keeps intervening on our relationship. Please help me.?

I've been dating my boyfriend Brad for 4yrs and obviously we had our ups & downs but in the end we stuck together because we love each other. Last year we moved in together and his family and mainly his younger sister Francine raised so much hell. Two days ago his mom Jennifer & Francine came over unannounced. I'm thinking they just came by to visit but I had a bad feeling in my gut too but I decided to ignore it. Anyway all three of them left and about four hours later he calls me and says I wanna break up and move out and live with his mom. Brad's 30 & I'm 23. I was devistated. I went outside to ask Jennifer & Francine what was going on. Fran told me he needs to move out to get himself together because he's living in sin. I tried explaining to him that was his decision to live with me and that he was happy. Brad said nothing he wouldn't even speak up for himself. He just kep saying he had to go. I believe while he left with him they filled his head up with some sort of lie. Last night he called me and told me he loves me and doesn't want to break up. He also said he wants to come back home with me but they won't let him. Then He called me at 2 in the morning saying the same thing. Then he called back at after church today crying saying he loves me, he wants to come home, but he just can't. What should I/we do? I told his family that I might be pregnant and they said they didn't care and that he has another child to tend to instead. Me & Brad were about to get marries, but they don't want him to marry me. I'm so sad. Please help.