How would u deal with in laws who don’t accept u?

My in laws are STRICT Christians & my mum in law is someone who dominates the family.

Right from the start, my mum in law has always been biased towards me bcos I’m not the ideal daughter in law that she wanted- I’m catholic (instead of Christian), don’t go to church, older than my fiancé & been older she thinks I’m infertile😡 (WTF!!! I’m pregnant now!!!)

She refused to meet my parents or been involved with our engagement. We don’t see her as much now bcos she loves drama & would pick on every single little thing about me to find faults in me & then backstabbed me over the phone to her son (I overhead the conversation when my fiancé begged her to meet my parents for the engagement gathering).

I feel upset & angry towards her all the time & at the same time I respect the fact that it’s his mum so we visit once a month. I feel left out when we visit his family bcos no one makes an attempt to chat to me (including his sis & her bf).

Don’t know what to do- how would u interact with ur in laws who don’t accept u? Also we’re married- how would u break the news & tell them we’re expecting a baby? My mum in law is a passive aggressive person who’s nice in front of me BUT backstabs behind my back- so how would u deal with this kind of person???😥 PLS HELP!!!