Problem with husband due to mental torture

My sister married one year back, initially everything was fine but later differences arises between them, main problem was he used to abuse her sexually and always show the money power and neglect her , by profession she is school teacher and her husband is a police officer, religion- Islam.Initially she tried to adjust her best but eventually she became extremely upset with her husbands behavior and left home, later she send a lawyer notice to her husband for divorce , her husband now raising many issues even trying to assassinate her character by narrating false stories in society , one hand he is telling he will not give divorce and she has to come back to him on the other hand he is asking to repay all the gifts he has given even before marriage, though all the items given during marriage are still with him. My sister do not want to go back to him, as such what legal steps My sister can take and how can she safeguard herself from her husband being he is a police officer.