Divorce for adultery

Kindly someone advise please! This case refers to my brother-in law. He got married some 12yrs back and blessed with two children also. He is a farmer and not educated much. His wife is more educated than him, looks beautiful and have desires beyond his capacity. From last 2/3 years somebody from a neighbour village trapped her and she began to make phone calls & chat secretly. Many times they met each other but can not be evidenced. She was caught while talking to him twice. Recently when it happened again, he told her that he can not live with and to leave the house. With the confrontation she left the house and do not the whereabouts. Next day he lodged a missing complaint in the police station. He has information that she is hiding with her new friend/ relationship & the case is now with police. What will the solution for this case? Can he apply for a divorce after her identification by the police? What evidence is required except her phone records? What is the way if she files a reverse case of harassment Kindly advise