After much thought I have decided that my own mother's family must have been a mess.
You do not grow up in a normal household with loving parents then get married and allow abuse to happen in your home.
She thought this was normal and okay.
After some investigating I now know for a fact that my grandfather was not the perfect man everyone made him out to be. My grandfather passed away when I was 4 years old so there are not too many memories of him there, other than his last days on this earth and his funeral. So my opinion of him was always what all my aunts and uncles said about him which was short of him being a Savior. Honestly they made him seem like a perfect human being.
I have found out that he was abusive sexually to some people. There are rumors that he fathered a child with my grandmother's sister while they were married.
I have also found out that my grandmother was extremely abusive. Physically, verbally and emotionally. She would beat children to the point of passing out. My mother herself told me of one time she was hit so much she became super sick for weeks and would not eat or leave the bed, she was about 7 then. There are also rumors that my grandmother cheated on my grandfather too.
I also know that my grandmother went almost 10 years barely speaking to my mother while at the same time expecting my mother to give her most of her paycheck to her mother.
It just all makes sense now though. This is the reason my mother has allowed this behavior, she grew up with it and so for her its normal and she cannot understand how I can be making a huge deal about it.