Family drama at its finest

So my husband and I have a weak spot for helping people. We always wanna help everyone that we possibly can. Here's what happened. My cousin came to visit for a week because her boyfriend hit her and she needed to get away for a bit. (Small back story both her and her boyfriend are recovering drug addicts. They were on heroin and crack really bad and I've been trying to help her stay clean) That was fine by me shes my family I'd do anything for my family her son was at his dads house so I let my husband throw a couple partys just for everyone to loosen up and have fun. 6 days after shes there she wants to see the dude that hit her. I said not a good idea but I'm not your mom do what you gotta do. A couple hours later she calls me begging me to let him come over because he has no where else to go and it was like 9⁰ outside. I talk to my husband, we make a bunch of rules and say fine but for one night. They stay everything's fine he seems really cool he apologized for what hes done and explained he was going to start therapy and what not. The next day comes and "they cant find a ride home" okay whatever stay 1 more night. The next day comes. Its valentines day. My husband and I go out for the evening expecting to come home to an empty house and they're sitting on the couch watching a movie. And its after 10pm 🤦‍♀️ so we let them stay the night AGAIN. I'm all for spending time with family but I barely know my cousins boyfriend and idk she had been there for almost 2 weeks at that point and I kinda just wanted my space back. I asked her "dont you miss your son" she said not really I needed the break.. I should have known then that this was going to be a long bumpy road. Instantly I get a bad feeling. So the next day she gets a call and guess what? Surprise shes been evicted from her home a half hour away and now had no where to go! So what do I do? Sure cuzzo you can stay here let me just flip my life upside down and adjust everything so you feel comfortable! Now before she came my household consisted of me (who is 6 months pregnant) my husband and our roommate. We live in a small 2 bedroom apartment but we moved everything around. My husband and i moved our things into the living room, my cousin moved into my bedroom and our roommate stayed in his own room. A few days after we decided to let her stay her perfect 2 year old son came home! I absolutely adore this boy and would do anything for him. The very first day hes home she is yelling and screaming at him for literally nothing. I observed and didnt say anything. The next day she said she had to go to her old house to get a few things and asked if I could watch her kid. I take him we go out for the day I come home shortly after she gets home HIGH AS A FUCKING KITE and says "we didnt make it to the old house today I'll try and make it tomorrow" atleast i think that's what she said. I could barely make it out she was nodding off the entire time. This has happened a total of 5 times since shes been here and I've been taking care of her son everyday because if I dont he wont eat he will be forced to stay in 1 room all day and he will get yelled at for doing toddler things like pulling out more then 1 toy at a time or asking the same question over and over again. Not only has she been treating her kid like shit and doing drugs shes been lying about it. She hasn't been paying she just got 1200 dollars and put 250 into the house to replace everything shes used. She ate all of the food we had in our house then when she buys food we aren't allowed to touch it or she gets really rude. Shes been flirting with my husband nonstop she doesnt clean up after herself shes just a wreck. She has an open child services case and still doesnt have her shit together. If it wasnt for her son I would have told her to leave so long ago! The point is you really never know anyone and you really cant trust anyone. Not even your own family. My husband and I have been fighting so much since shes moved in but it's not because we are mad at eachother theres just so much tension its unreal. We want to help her son and honestly she needs to just help herself right now. I have my own child to worry about. And get ready for. But how can I protect her son without her continuously ruining our lives?