Cheating wife and Child custody

We are married for more than 8 yrs and have a son 6 yrs old. My wife is 5 yrs younger than me, very immature, egoistic, and inclined towards her parents who aren't very well off. We have common relatives and our homes are very near (1km). My wife's parents had extreme interference from the beginning. She often misbehaves, then when I explain her instead of fighting, she apologizes (sometimes in writing). We are basically forgivers. But when she does something what I disagree, she tortures me till morning until I forgive her and pamper her. Sometimes when arguments take a heep, she silently calls her parents and they immediately come to our residence to fight and threaten. Many times she has left the house and everytime apologizes and I get her back. Like her parents, she is also very over possessive for our son, but often she is negligent as she is very very self obsessed. Since 2 yrs, I am insisting to have a second child and she is constantly refusing and starts a fight. As my son has grown old, now she had ample of time to have an extra marital affair with a married neighbor and it had started recently. Also she had started to record our conversations in her phone since she returned from her maternal house (why?). Though it doesn't make a difference to me as I never misbehave. When alone or in daytime, she usually started shutting the CCTV power (agreed to lover in a call) (why?). Two months back, I caught her red handed as I heard the recordings of her with her mother (my wife abusing me and my parents, and her mother teaching her not to have a baby and enter our business and make some spying settings in her mobile), as well as lover (desperate and inviting talks and agreeing to share private pictures). Her parents came to fight as usual, and took her and my son with her. Before leaving, she apologized to me from guilt and promised to come back in 2 days and never return back. But surprisingly, she filed a complaint of DV in CAW cell. The hearings have started. There she says 1. I and my mother are violent to her, 2. She wants to live with me alone, 3. She wants her IDs and documents, 4. I dont care about my son. After giving her all my trust, love, and care, what I got is disrespect, distrust and conspiracies which she learns from her family. I have done all that I could do to save our marriage. I cannot live with her anymore as now I know everything. But I dont want my son to become like them. I want him back. I went to meet my son at the school and give him his favorite toys, from the next day they are not sending him to the school as she fears that I will take him away. Yes, he is not going to school from more than 1 & 1/2 month. I am depositing the fee though. I helped my wife do graduation (BA) last year and she is a housewife. My son's future is my only concern. Please suggest a course.