HELP!! I need advice, (longggg story)

So I met my boyfriend last June, I’m 18, he’s 22, one of my friends is dating his brother and that’s how we were introduced. I was a pizza delivery driver at the time and would deliver to the campground he worked at so we would always meet up, we quickly figured out over a few months that we were the ones for eachother, he really is the perfect man for me. Him, his 4 year old son from a previous relationship, his sister and parents all lived with his grandparents at the time and that’s where we would hang out. His mom is a heroin addict and the grandparents eventually stopped letting her in the house so she was living out of the car. In October we helped his dad find a place for all of us to live, without my boyfriend his dad wouldn’t have been able to afford it so we split rent with him. Soon after moving there his mom started working at a fast food resteraunt and although we thought she was done with drugs (she seemed to be acting fairly normal) we started finding needles in the bathroom and she was stealing her husbands car and leaving in the middle of the night. She has spent plenty of time in jail and has a parole officer that comes and visits. She recently got a puppy for free and brought it home but didn’t buy any food or anything for it so I took care of it, bought it’s food, collar and toys to play with. Her parole officer had a surprise visit last week and his mother refused to take the pee test and admitted that she would fail for meth. Nothing came out of that but her parole officer required a follow up test on Monday. Sunday night which also happened to be my boyfriends 22nd birthday came around and his mom started arguing with his dad around 2 in the morning loud enough to wake everyone up. We stayed upstairs to try to get back to sleep, around 4:30 in the morning she took all of the dog food I had bought with my own money and her daughters laundry detergent, stole her husbands car key and left in the car. We found out yesterday that she showed up to her parole meeting and pissed dirty so she was sent to rehab (for the millionth time), and our dog is nowhere to be found (most likely sold for more drug money). Now that’s just his mother, his sister (who’s my age) although I do like her she’s well known for snorting lots of pills and her dad not only supplies her with them but enables the mothers behavior. I’m currently 17 weeks pregnant (unplanned) and all this does is stress me out, I don’t want my baby to ever even meet his mother and don’t even want him around any of these people just because of awful things his mother has said and the fact that she’s just proven herself to be an awful person in general and the fact that drugs are so prevalent in the household. Any opinions on what I should do? My boyfriend already knows all about my opinions of his mother and agrees with me about her but I haven’t told him about how I feel about his dad and sister because I know that would upset him.