My mom finds fault with my dad daily and in turn he curses her in a very profane and disgusting manner. They have been married 56 years and their anniversary was June 19th. Their relationship has been bad since I was 10 years old, yet she won't divorce him. I grew up hearing the cursing, verbal abuse, watching him physically abuse my mom and older brother. I live with them also.
I'd look for work opportunities nearby, but not too close. It doesn't sound like your mom is going to get cooperative overnight. She sounds quite stressed, and almost certainly depressed, as you point out. You are smart enough to recognize your depression.
Learn about setting boundaries with your parents, and about FOG ( fear, obligation and guit)
Wishing you lots of luck finding a job so you can move.
Do either or them take medication for depression/anxiety? That might help, but I think I would inform them they need to make arrangements for their care and a time line of when you would be leaving. I'd find a place to move first. Unless you need to live with them for financial reasons. If you cannot afford to move out, then I would try to find a job and then move out. becoming a caregiver for person who once abused you is very concerning. I can't imagine it.
Do you really think that if you tell them how you feel that they will change their behavior and the way they interact? Do you think they would attend therapy to get help with their behavior? At this stage of their life, I think it's highly unlikely.
I might attend individual counseling, since there seems to be pain from the abuse in your childhood. I wish you the best.