I hate living in my own home

So I live with my fiance and our 3 month old son. My 17 year old cousin lives with us and has since before my son was born. Recently my mother has had some health issues and she has moved it with me. We don't have a good relationship and she wasn't there most of my life as she was an alcoholic my entire life. I grew up I foster care. Anyways my grandparents talked me into letting my mother move in with me they kind of guilted me and told me they would come around more and I really wanted my son to have these people in his life but it hasn't happened. My cousin was supposed to go back to his mom but she is so flaky and has yet to auctually come get him. I don't think it's gonna happen. So now I have a 17 year old in my living room at all times. I can't do anything. I can't clean I can't watch TV I can't relax. I'm stuck in my own room all day long with my son because I don't want to hang out in my living room with a bunch of teenagers. I'm getting so fed up. Idk what to do.