I don’t know what to do. I live with both

I don’t know what to do. I live with both of my parents. My dad is 80 and my mom is 64. Both my mom and I are disabled so my dad is working incredibly hard to take care of us.
My mom has always had a reputation for being rough around the edges. She will be your best friend unless you make her mad and then you better watch out. My parents have been separated since I was very young and have only stayed legally married because it’s too costly to get a divorce. Ever since I can remember my mom has found reasons (some of them justified) to be mad at my dad. He cheated on her when they were together and she has never let him forget it. Her getting mad at my dad has become a very normal thing but now it’s different. Now she gets angry with him over things that any reasonable person would think are not worth it and some are just flat out crazy! She wants to control where he goes and who he sees. She tracks him on her phone and if the app isn’t working right (which happens often) she accuses him of turning it off which fuels her paranoia. My dad doesn’t know how to use a computer much less know how to turn off an app. When she yells at him she speaks to him with such disdain and disrespect! She constantly brings up how he hurt her decades ago and is always “keeping score” so when she yells at him she can bring up all that she does for him!
Up until a couple years ago I thought this was normal. But now that I’m older I’ve come to the realization that my mom is emotionally and verbally abusing my dad. My dad is the most meek and gentle person you will ever meet! He will avoid confrontation at all cost! He’s working his tail off at an age when most people are retired and he’s supporting both of us! He does have his faults and he can drive me crazy but he has done nothing to deserve this kind of treatment.
My mom did not have the greatest upbringing and was abused. She says that she’s left all that behind her but it is very apparent that she hasn’t. She hates men. She hates anything my dad likes and is extremely jealous of some of the students he teaches to play piano. It seems like every single day there is some new petty thing that she is upset about and the environment in our house has become so toxic.
I don’t want to confront her because she scares me and I know how stupid that sounds but it comes from a lifetime of her blowing up to know that if you step in between her and my dad, you’re going to pay for it! Whenever I try to intervene she accuses me of “ganging up on her” with my dad. Now that I know that this is abuse I have no idea what to do or who to turn to. I used to use drugs to escape and I can’t do that anymore so I don’t know what to do. Does anyone have any experience with other this kind of thing or should I look somewhere else?