How can I help my mom?

I’m a 27F and my mom is 52F. She’s been in a relationship with my stepdad for 25 years. They never married and their relationship is miserable. My stepdad has a lot of mental issues (apart from bipolar disorder), he’s extremely jealous, a pshycological abuser, he’s sexist, incredibly close minded, paranoid, etc etc.

At the moment they started dating each other, he didn’t let my mom work or have any friends. In the past, he accused her of having multiple boyfriends (created in his own mind) and was even jealous of my mom talking to her brothers. As toxic as it gets. My childhood memories are full of them breaking up weekly and my mom crying for hours in her bed because he broke up with her (this happened hundreds of times). If she wanted to take me to the mall, it was at some moment where he was sleeping and couldn’t be for more than 1 hour, if he started calling, we would rush to the house, and there started another fight. I never developed any strong relationship with him because of his personality and because I spent most of my childhood living with my grandma, though.

My mom is completely alone now. Absolute zero friends, she only talks to her close family members, and nothing has changed in their relationship. She doesn’t go out on her own when she’s with him. He drives her anywhere she wants to go. She wants to walk her dog? She goes with him or if he’s not home, she calls him and tells him where she’s going. When she comes to visit me, they talk at least 20 times a day (I’m not exaggerating). They don’t talk about anything really, it’s just her trying to update him about what she’s doing. I spent one week at his house visiting my mom and it was the most depressing relationship I ever saw. They never talk other than about his work problems. When they’re on the car, no conversation, no sounds at all.

Not a minor detail, he lives with my mom and his brother (58M). His brother is deaf but is in perfect health and because my stepdad has mental issues, he takes him anywhere with him. A restaurant dinner? A table for three. His brother is really humilliative towards my mom also. He demands her to wash his clothes and his dishes. My stepdad supports him 100% of the time.

My mom is a professional, she worked at a bank before meeting him and was very succesful. Now, she’s a extremely insecure woman, she can’t even drive properly because all the physcological abuse she’s subjected to. My stepdad treats her very poorly. He humilliates her and constantly tells her she doesn’t do anything good. I’ve seen her mental health deteriorate, her emotional codependence is even more ingrained now. I’ve told her million times that she needs therapy, that she needs to get out of that toxic relationship. She tells me that she “knows” all of that and tells me to shut up. She has stopped talking to me for days just because I mention her that they should break up.

I don’t earn a lot of money, but she could totally live with me. She says she’s only with him for money and because of her age she wouldn’t get a job, I don’t think that’s the case. I’ve offered her to live with me but no, she’s unable to leave that man. Well, she’s even unable to be at a different place and not calling him every 40 minutes to tell him what he’s doing.

He won’t break up with her. He needs her. She does a lot of his work, she buys the groceries (he accompanies her and stays with his brother in the car), she attends all of his phone calls (because he “hates” people and suffers from social anxiety). And he also does not have any friend or family member he talks to (he fought with all of them).

\*\*TL;DR; : It’s so sad to witness her toxic relationship. It’s sad to see my mom live like that. I don’t know what to do; trust me, I’ve talked to her in different ways and she gets mad everytime. She’s in her pajamas all day and never dress up. She’s not happy. What can I do when she has such a strong emotional codependence? How can I help her?