Soon to be MIL is ruining my life psychologically.

Kana

this is probably gonna sound controversial so i decided to post here. backstory: me and my fiancé are TTC a little sibling for our daughter (nobody but us two knows), my fiancé isn’t her biological father, but he’s been there for her since she was born. it’s obvious his family treats her differently from my fiancé’s nephew who is blood related by his sister, but especially his mother. shes petty, passive aggressive, and never really acknowledges our daughter trying her little heart out to play or hug her. she acts like our daughter is a nuisance for doing things every two year old does. my fiancé’s nephew on the other hand is a month away from being two and they treat him like gods gift to the earth no matter what he does or how destructive he gets (throwing glass, hitting the cat, screeching his lungs out over being told “no”) he even went so far as to bite our daughter and left teeth marks in her arm but i was screamed at for “pushing him” off of her (i really gently and calmly pulled him away quickly so he wouldn’t BREAK HER SKIN WITH HIS TEETH) my fiancé has completely lost faith in the people he thought he knew as family and is ashamed of them. we’re on hard times trying to move out so we’re stuck living with his parents (only “relatives” we have in state) until we save up enough (thanks COVID) we cant really push back too much on the mistreatments or we risk losing the roof over our heads. idk what to do and tonight was the straw that broke the camels back as my fiancé’s mother told him behind my back “i wouldn’t mind your kid being out here, but she cries” (as if “her baby”/fiancé’s nephew didn’t literally scream bloody murder all day long at the drop of a hat) we live in a single room and pay half the rent plus a bill or two and buy groceries for everyone and we cant even go into the rest of the house just the bathroom!!!! ~$800 every month just to sleep eat and live in a single bedroom with three people in it!!! and don’t get me started if i want to buy my own food or god forbid go to the store in my own damn car. i really just want to know if i should shut up and be grateful i even have a place to sleep or if i’m the bad guy here for wanting to become part of my fiancé’s family.