One of my best male friends got married two year back. after marriage he found that his wife has phy

One of my best male friends got married two year back. after marriage he found that his wife has physical relation with other person. He recorded her voice/call conversation with that person in mobile. He has sufficient audio recordings of both which clearly shows that they are in physical relation. As he came to knew about this matter he tried to solve by mutual talks but no result at all. After this they both filed mutual divorce but after 6 months period his wife changed her decision and refused for divorce. Now she forcefully living with his parents home and not ready to go her parents home or outside. She is making pressure to live with my friend on any cost. My friend don't want to live with her because she is in relation with other man and also harassing his family members. Every time she threat to file dowry case on his family. Please suggest us in proper way so that we can get rid from her. He wants divorce at any cost.My friend is a Hindu