What's up with my boyfriend and his family??

Me and my boyfriend have been together for a year. It was fun in the beginning until I accepted the invitation to move in with him, his brother, sister in law and their 2 kids. Living with them was fine at first but my boyfriend was starting to have financial issue (he pays half their rent). And also got his car repo so I had to help him out with that. His sis in law helped out a little bit too. But I lent him the majority of the money. We have gotten into many arguments mostly involving his family because I remind him that he is paying half of their expensive rent and he keeps insisting he has to help. He barely has any to give! He says no one else In his family, aunts uncles help then out (I wonder why). Lol anyways my bf pressures me into becoming friends with his sis in law which we hung out once. After that one time I kept inviting her to hang bit I have up when she told me and my bf she was going out with her friends one Sunday. So I said ok I give up, I've been asking her to hang but never mind. I recently moved out to get my own place and now my boyfriend tells me to spend the night over his bros. house as well. I'm not comfortable going there. He week I moved out the bro ask me if I had. A mattress I said air mattress then he was telling me where to get affordable mattresses. Ok cool. But the day I move out, a couple days later he ask me in front of his wife and my boyfriend if I have a mattress. I said again air Matress. Then he said "air mattress" and kind of snickered. Like a little laugh. I'm pretty sure he was talking to his wife about me the reason he did that in front of her. My boyfriend doesn't realize I'm not comfortable being around them anymore. And he had the nerve to compare me to his sis in law a couple times before like "you should do such and such like her." We got into a fight and I said "really you're comparing me to your sis in law...well why don't Lu date someone just like her!!" Clearly his bro and sis in law have an issue with me for whatever reason. What should I do?