Serious questions about MIL

Before reading please no hate, I’m really looking for advice on my situation..

A little background,Okay so I’m due in sept & a first time mom. I’m 20, (my bf also 20) we’ve been together for 5 years & I’ve about seen it all with his mom, or I thought. Since we’ve met he’s been a mommy’s boy, and her being all about her son. Even admitting to him, he’s her favorite (out of 3.). She’s always been not my favorite person. We don’t speak the same language, so there’s always been that added barrier. She’s been off since I’ve met her. Doing things like asking why he doesn’t kiss or pay attention to her, when he would kiss my cheeks or even lips.. not let him see me when we were younger bc she “said so”, making him take photos of him in quite frankly, inappropriate outfits, telling him about her affairs with other coworkers (mind you she’s married to his father of course, for years.) making my bf take photos with her in prom like poses (him holding her waist) etc etc I can really go on, especially about her allowing & buying the daughter clothes like crop tops, short outfits & clothes too tight (on purpose) anyways like I said I can continue but I’ll get to the point of this post... since we announced were pregnant she’s been happy of course & wanted grandchildren (according to her later on though & doesn’t want to be called grandma.) she is very much still trying to be in her youth (although late forty’s) with makeup, cleavage, tight short clothes, clubs (yes, clubs not a bar) etc.. (YES ITS HER CHOICE & HER DECISION TO LIVE HER LIFE) but it’s unfair to me when we’ve been called at like 9/10 pm to babysit randomly without any earlier notice & were expected to go babysit for her to go out, and mind you.. the daughter cannot read. (She’s 12, and cannot read.. even the word boy. She isn’t mental or anything wrong, just neglected & not helped by her parents). anyways!! Recently the mom on multiple occasions has said “the baby is hers, not mine, hers” (in Spanish then translated to me) but as a “””joke””” to me, it isn’t funny & when it was said by her, there was no laugh.. I should also mention how that ^ was said more then 3 times, also how we’re moving into there house soon, bc my brother is an addict. (We’re currently living in my room at my moms house.) we have nowhere else to go so its the only option but I dislike her, another joke made 2 days ago was .... “she’s going to give me the papers & paperwork for the baby to be mine right?” (In Spanish, translated to me, as a “joke” but again, no laughing & I do not find it funny... nor have I ever heard that “joke”) she has said a lot more things too like if I’m going to let her babysit “alll the time” although I’m graduated & currently not working or planning to until a little further down the line, my boyfriend currently is the bread winner. I fear of being there when he’s working & her being home & her taking over. I can see her telling me what to do, always being all over me, including the little girl too, who I do not have to babysit but it would be a job given without notice as soon as I move in. They don’t trust her so currently she goes daily to the fathers job at a mechanic shop but is constantly bored wherever she goes or is. (Including if we try to take her out for a little walk or errand.) anyways idk what to do or say I’m afraid to mention this all to my bf because to him it’s really just his mom “joking” to me it isn’t ...if you say the baby is yours multiple times I’m going to start being weary of your “joke”.

Imagine a partner saying to your friend “imagine if we kissed, nah I’m jk” you’d be weary of it I can imagine .. idk.. let me know down below