Husband harrasment

Hi, This is on behalf of my sister, who is married 15 years ago and has 6 kids (4 daughters & 2 sons); her youngest son is 2 & half years old. My brother-in-law is a maniac, he tortures her mentally and physically YES, physically after 15 years of marriage with 6 kids. He is hitting her badly such that at times she describes even doctors have asked her to tell them that her husband hits you? Even after suffering such huge pains she kept quite till now & if you ask me the reason it’s pretty simple as we are FOOLS thinking of society, kids and what people will think? How it will affect my family? What about my family and my reputation? I have four daughters, who will marry them? How I’m gonna live bla bla bla bla. But, now she is fed up with his tortures as she got hit very badly from one of her recent incidents. She even thought of some very bad things like suicide. She wants divorce from him immediately as she is scared so much that she is saying he might behave well and again take me home and after some time (hardly a month) the same process will begin again, she is thinking in that manner because it happened in past where he tortured her and later apologize and few days or weeks then it starts over. She never came to us (brothers/sis/mom) describing all the above situations ever. But, as the torture has increased so much because from past 3 months he is just sitting at home and torturing her every single moment. Please I need help to take her out of this situation and give her freedom. I was literally crying when writing this letter thinking of tortures that she suffered. I was searching for the possible options for her in this situation that’s where I ran into this website. I humbly request you to please advise me and explain me what can be done in such situation. My sister is even afraid of his husband’s family because one of his brothers is an advocate and he has some political influence, etc. Thanks!