How you can get child custody?

I am govt servant and my wife has B.sc nurse qualifications but she is a house wife. 2 children a Girl of 6 year. and a Boy 4 year. I caught my wife cheating on me. She herself claims she is in relationship and wants divorce from me. She said she’ll file a divorce and will take the children custody and also file for maintenance. I have decent proof of her link with the man. Plz help. Can I get the custody of my children without giving her maintenance? I don't want divorce bcz of my children but she want and she is openly talking to him which has become intolerable for me. I’ve video of them meeting (compromise position), few screenshot of their chats that I took before she erased it all. Some audio recording that I took of our conversation (without her knowing). She wants divorce at any cost. I am compel to agree but want custody of my children and also no maintenance since it's her that had committed extra marital affairs