Divorce Case

Problem is my sister life(iam brother) We living join family(rent house) father, me and sister, husband and 2 year baby girl. Married 4 years happened, from marriage always fighting each other, thatsy living together join family last 2 years. But now problem 1 month before, husband beating wife in front of the road, my father and me asked and send him out from house, after 5 days relations talk to us and joined together same house Now problem: He giving mental torture to her, verbal abuse, Alcohol drinking, unemployment, illegal contact and psycho activity in bedroom. So She clearly decided divorce, but he not accepted, not vocate the house and ask the baby girl, If We asking father and me, he fight with big shouting and abusing word, we Spoke his relatives, did not take response, iam getting worry and tension, because going to marry next 4 month, so cant spend more money and time . How to handle this situation, how to proceed the police station, She and her child going to live with my family, Again he make trouble, how to handle (beating or according to law)