My wife was cheating me illegal affair with her brother iin law

Sir my wife was cheating me with extra matronal affair with her Brother in law she always tell lies oneday she went to her brother in laws house with out knowing my knowledge there she got fractured on her leg. She was operated I ask her what happend then she told that my leg was slipped and fall down at my home after six months my 4yr old son told that dady mumy was fall down at her brother in laws house then I asked her about truth after some discussion she agreed that she had sex with her brother in law then I took her into their.home I tell everything to their family members then they are attacked me she changes her statement she told that he is trying to put illegal relation with my brother in law after that they want to police station and put bind over case on me SI of police station is also showing partiality in my case he is showing favour to them I want divorce at any cost please help me with suggestions I gave 15lakh rupees to my father in law for investment through bank. How can I get my money back sir please help but I don't have any evidence because of blind faith on her if she put a 498 case against me and family what should I Do