I wish my dad would take my mother's side but nope he doesn't respect her one bit and they get into multiple arguments everyday. My dad is super overprotective of everyone in the family, including my mom. My mom works from 3 pm to 11 pm and my dad gets extremely paranoid that she's sleeping with another guy so he drives by her workplace just to check up on her... he also picks her up. It's pretty sad that someone can't trust their significant other and this has been happening ever since my mom was married. My dad is overprotective of me too, he would never let me sleepover at a friend's birthday party unless he's close to the parents.
My dad is also physically abusive towards my mom (and brother). The police were called to our apartment once because me, my mom, and brother were all screaming for him to stop abusing my mother but he wouldn't. We moved into a house quickly after which I think my dad chose because nobody could hear him abusing the family.
My parents got into a fight again and I was watching them since they were literally screaming off the top of their lungs right next to my room. My dad had enough and pushed her down the stairs... my mother's head cracked open and blood spewed everywhere, mind you I was only 11 or 12. My whole family was in tears but my dad continued yelling at her and telling her she deserved it. I grabbed my mom's phone to call the police while yelling vulgar names at my dad which I've never done to anybody in my life. He just snatched the phone out of my hand and kept yelling at my mom while her head continuously bled, and it was a lot of blood. It was the most traumatizing thing I've experienced in my life, currently suffering from PTSD, and it's something that I will never forget.
Ever since then I hated my dad. He never abused me and always spoiled me but I didn't care. I didn't talk to him, look at him, or accept any of his gifts for a long time. Growing up I was a daddy's girl but I was devastated and heartbroken, I'd never be the same around my dad. I wanted to do the same to my dad, I wanted to pound his head on the side of the concrete until he bled for hours on end. I've even had involuntary thoughts of murdering people at my school or strangers walking down the sidewalk. I was a miserable teenager thinking about suicide 24/7 and didn't want to go to school because of my severe SA but didn't want to go home to face my dad abusing my family.
Five years later, I'm still hostile towards my dad but I've forgiven him. I talked about how much his abuse towards my mother led me to believe he didn't love her or the family. I never thought I'd be talking about this with my dad let alone ever have a normal conversation with him again, but I did and I'm glad I did. He comforted me and told me that he'd love my mother till the day he dies. He also said that he loved me and my brother unconditionally, and if he didn't love the family he wouldn't be going to work everyday to provide money, food, and shelter for us. I told him that abusing the family emotionally and physically isn't a way to show love so he apologized and said that sometimes he and my mother get into arguments and it's hard for him to contain his anger but he'd try his best to avoid it. I accepted his apology and that day, I was the happiest I've ever been for a long time.
It's not going to be easy because it was one of the hardest things for me to do, but you have to forgive and move on. For me, it didn't happen until I sat down with my dad and talked about it so maybe if you try that with your mother you will find it easier to forgive her. It's a choice to hold a grudge and there's no point on having one.