Sister in law !!

Im currently 27 weeks expecting my first child (a boy) & my sister in law is pregnant too "accidentally" and she's 25 weeks right now. She's very known to be rude and act superior than others. That's her 5th child & it's going to be a girl. She always thought I was having a girl and was happy because boys in my husband's family are "better" than girls & she has 3 girls and her last one it's a boy so she wanted him to be the last boy of the family or to have a boy with this pregnancy. Since she found out I'm having a boy & she's having a girl things been rough because she thinks my son going to take her son's place which it's stupid. My husband already has a boy who's 5 yrs old now and she was so happy to have a boy last year because her son would take the "favorite grandchild" place 🤦🏼‍♀️ and now my son going to take that " place " specially since my MIL has already expressed it . She hates her pregnancy just because it's a girl & be talking about my unborn child saying he's going to be bad, and he's going to be no good when he grows up. I want to raise my son as far away from them I can but she be all in our business making comments all the time like " oh, he don't move much in the belly, wait for him to be out here. He's going to be a disrespectful misbehaving kid" & I don't even know how to say sometimes but I hate those comments she even have tried to say my stepson is not my husband's kid & he literally is my husband's twin. She always wants to make it seem like her kids are better than her brothers kids (my husband). My husband has put her in her place but she keeps going & going. What should I do ?