How can I help her?

Long story short, my parents are toxic together - she’s a pushover, he’s an alcoholic narcissist. Seeing their relationship is like watching the same car crash happen over and over again. Usually it goes like this: he gets explosive over something petty, is rude to her, she gets upset, he promises to stop, she gives him another chance. It’s exhausting. This last time, it was actually a huge explosion w me, but ofc he escalated things and it ended up somehow w him telling her she didn’t own the house even tho she works bc she once was a SAHM and threatened to kill himself, exactly the same way her brother had, before storming off. It was horrible and I really thought they were done, but I was wrong ofc. My mom said she “wants to be able to look back and say she tried, have no regrets” so she gave him one more chance, but this time told him that he needs to do something to help him stop drinking and they’d go to marriage counseling, otherwise she’d take us and they’d separate.

I knew this wouldn’t work from the beginning. The problem w people like him is they don’t see a problem w themselves, and even if they do, they don’t want to be told about it, so he wouldn’t go to counseling. It’s only been a little over a week and he’s already back to it. You can tell bc he’s back to having an aggressive attitude. He even crashed into a curb the other day and tried to manipulate my brother to lie about what happened. He also turns his location off whenever he comes home from work. I told my mom I knew this would happen before it did when we talked.

Now that he’s back to it, she’s having the same hurt that she did before. She texted me saying she’s done being stressed out and constantly feeling like she’s in trouble. I feel bad but idk how to help her. She’s too nice to leave. But it only keeps the revolving door open