Need Advice On Two Demons

my bf has three sisters and no brothers. I was 17 when I got pregnant w my bf and at first I got along with all his sisters. We took a family trip to Cali a yr and a half ago and it turned out horrid! One of the sis who was 18 at the time was calling me fat and ugly when I know I'm a really attractive girl. I went to buy juicy couture sun glasses and she said how ugly they were ect! Than the other older sis jumped in and saying stupid stuff on how I'm jealous of them..? So we came back from the trip and since than everything has been akward and worse. I got pregnant and they continued to disrespect me the father my fl he threatened that he would kick them out if they keep at this behavior. So they did it when he wasn't around. I took it all in since at the time I had no where else to live and me and my bf have a good realTionship. So after the baby came they continued and I got in they're face and hit one of them the one that stRted it all at she's 19. I know I shouldn't have done that but they are so meAn and I never did anything to them I feel so betrayed hurt judged. So it made things worse. So they got kicked out for starting it and I did to but they let me stay. So the two sis finally moved out it's been 4 months now but they stay here like everyother day. At times they're still disrespectful of me. Two days ago she tried telling my son that his grandma was his mother infront of everybody!! I told her that's not his mother she rooked thats what I call her! At leSt my mother in law told her not to say that! Honestly I hate these immature women who graduate at university's and they're still dumb and cruel! My bf who I call me husband at times bkz we plan on getting married, agrees with my and sticks to my side he knows his sisters are wrong for how they act. I just don't know what to do I'm sick of them. I don't want to move out of his parents house I'm 18 and basically I never had parents just a grandmother who's reLly old now. What do I do? Please