I absolutely loathe my soon to be mother-in-law

I've been engaged to my fiance for 3 years now and we are currently expecting with the babies due date on march 23, and her mother is horrible and conceted. her mom sits there and doesnt support her daughter and say's that im abusive towards my fiancé but i have never laid a hand on her, like really why would i hurt the woman i love and want to spend the rest of my life with. her mother also is very much against her daughter and me getting married becuase she thinks we are getting married because we are expecting a child and we clearly not getting married because of that as the main reason we are getting married because we love eachother to the moon and back. her mother also thinks thats she is better than everyone because she has money and her husband has a s**t ton more money and say's that we'd be better off if my fiancé miscarried and we had more money but we obviously have money and our own place so what are me and my fiancé doing wrong or missing and how does she get off calling me abusive and being one of the worst peiple that i know.