A visit to my sister

I went to visit my sister today. I am sorry to report that she has had another relapse. She has lost the weight she had gained. She told me she wasn't eating again. I feel like we are back to square one. She has no desire to leave or even try to get better. She worries about things she has no control over. She worries that her children are not being taken care of. She has two children in college and one that is 14 yrs old and still living with her cheating, cruel and terrible husband which as someone commented conveniently forgot the part in the marriage vows that say in sickness and in health.
Also he is the reason she is sick now. We had a long talk....4 hours and most of it was about her finally coming to the terms that yes indeed he is a jerk. I am glad she realizes this. My parents tried to help her, but she could not see past the part about being true to her marriage....no matter what.
I feel bad for her kids. They had to grow up in that household with their father being cruel and hateful to their mother. And now their mom is in a mental hospital with no hope.
I tried to encourage her the best I could. She mentioned that her doctor was trying to get hold of me so that I could take her out for a few hours and go out to eat or shopping or something. I told her just to let me know and I would come and we could do whatever she wanted to do.
I feel caught in the middle to an extent because I feel that the doctors should know that she is not eating. She tells them that she ate at the coffee shop. When in reality she is just not eating again.
Not sure what to do because if I do tell them....they will tell her I told them and then she won't trust me anymore.
I want to be there for her and help her in any way I can. But right now she has her mind up that things are never going to change and that she is just going to stay there for the rest of her life. She is only 50 years old.
She says there is no reason to get better because she will never have a car, a job or any reason to be out.
I wonder if they have changed her medicine....or maybe she is not taking it again. You know...pretending to and then spitting it out.
I miss my big sister. I wish that I would have known all this was going on. I would have MADE her leave him.
He is still having an affair with a married woman. He is still married to my sister.
He is the type of guy who is a charmer and everyone thinks he is a good guy....he isn't.
He does not have me fooled.
It's been a long day.
Barb