Divorce for my sister

Dear Sir, My sister is married for 10 years and has daughter of 7 years. My sister never informed us the kind of threat she was going through. The person is drug addicted and also used to drinking.He is from media.He has tortured my sister after marriage and especially after the birth of their child. He had also misbehaved with his colleagues in his office and a case was also filed in Chennai against him. My sister took transfer to Kolkatta and from past 6 years every year for 5 or 6 months he goes mad.He will drink the entire day,break the household items,does not allow my sister to go to office. He is insane.He has an ego prob as my sister earns more than him and he has ruined his career.He just wants to get rich. Every year he says that it is the last time but it gets repeated.He has started the same case again from past 10 days.My sister and her in laws came out of the house and staying with my brother. Today he reached at my brothers place and broke hi LED while he was not at home and threatened my sister that he will not leave anyone if she does not return home. My sister is reluctant to take any police help as she says that what will happen once he comes back from jail as he was saying that he will not give divorce to my sister.She is very scared. Thanks, Madhumita