Different point of view 😓

I need some advice I guess I could call it that. In truth I'm not really sure. I'm 14 weeks pregnant and me and my fiancé don't really get along the best right now. The day I found out I was pregnant his mom text me asking me if I was pregnant, I told her I wasn't for sure but I knew I was about a week late. Normally it wouldn't have been a big deal but for some reason she made it out to be this big huge thing. My aunt asked me the same thing and I told her I didn't think so but why would she just come up to me and corner me about it. She went and got me three differwnt tests and as soon as I took them she took them outside where her, my fiancés brother and his sister were and wouldn't even give me the chance to see them. All she told me was it said that I was pregnant. My fiancés brother came in the house where I was and threw another test at me and told me either I take the test or I pack my stuff and leave. Honestly that hurt but I didn't really care. So I took the test and he told me that I needed to go away for about a week and then I could cone back. It being his house I had no choice but to listen. So I came back and I tried talking to my fiancé about the baby but every time I did he changed the subject like he didn't want to talk about it. Now since word has gotten around about the baby he continues to tell people he doesn't believe it's his. I've had four people come up to me and ask me about it but when I go and ask him he gets mad and says he didn't say it. All in all I feel as though his family is pushing me to get a DNA test done on the baby and I'm fine with that but whenever I try to share my being happy about the baby they act like it's the worst thing in the world to ever happen. Now before I was pregnant I will admit I smoked pot but when I thought I was pregnant I stopped right away and haven't touched it since. My fiancés brother is really bad on pills. He's so badly off that he's stolen money from me and my fiancé to buy pills. He's been known to pressure my fiancé to snort pills with him. Well my fiancé told me a few days ago that he and another of his friends have snorted tabs and coke. I'm not exactly sure how to feel about that. On top of that, when he does it he gets mean. The last time he done it he slammed me on the bed a few times and the bruises started showing up two days ago. I've talked to my aunt about it and she says it's just best if I leave. When she says that all I think of is when I grew up without my dad, I thought it was my mom's fault that my dad wasn't there and I hated her for it, what if my little boy thinks it's my fault and he ends up hating me like I hated my mom. I love my fiancé I do and I don't want to leave but I don't know what else I could do.