How can I help my sister?

She is currently in a toxic abusive relationship with her baby daddy. 23F and has 3 kids with him.

She drinks 2-3 MD’s a day, that or beatboxes and she gets pretty messed up and isn’t a bad mother to her kids she’s just very annoying and blunt which is why they fight so much. A night or two ago she came over to my house with a black eye and did not remember whether it was from her punching herself or him punching her. She usually always has bruises on her face, legs, arms, but blames them on the kids or other things. She mentioned that he was very apologetic in the morning but then switched to make her think she did it but she defends him no matter what. Our entire family does not like him because of many other situations but she heard from a friend that he’s going to try and get the kids taken from her because of her problem. He constantly judges her even sober and is pretty much the reason she drinks. But the second you mention AA she shuts down and gets defensive about her problem.

My sister is an amazing mom and is their sole provider besides him not allowing her to spend her TANF on them. She is unable to get a job because he won’t let her. She is unable to get her license too because she constantly has her three kids with her. And I honestly don’t blame her for drinking. But I think she deserves better. I hate how she defends him. But I also can’t stand her in ways when she’s drunk. But it’s the only time she is happy.

To any former/current alcoholics, or people with knowledge about them, what can I do to help her make her way to sobriety without her taking offense?

She is my best friend and I hate to see her so sad. Please help me help her.