My fiancés mum treats me like a stranger after 9 years of being together. She excludes me out of every gathering and my partner never on my side. Should I leave the guy?

She came into our house on his birthday and wouldn’t even say hello and not even talk to me. Then she excludes me from every single gathering.
My father just had a heart attack and she couldn’t even say sorry to hear or care..
My partner is always on her side and says she is so nice to me!
He never even cares how much it hurts.. and my family are so nice to him and include him in like family.
I am a very family orientated person and thinking if I have kids with this guy what would happen if she is like this to me.
should I leave this guy as life would be so hard with him always on her side and never listening or caring about me?
My fiancés mum treats me like a stranger after 9 years of being together. She excludes me out of every gathering and my partner never on my side. Should I leave the guy?
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