WHAT to do if my wife is cheating on me with my boyfriend

Hii m 25 years old and my wife is 23 years old, we got married 2 years before in april 2016. i have found my wife is cheating on me as i have got her intimate pics with her boyfriend in my bedroom. i got this pics from her boyfriend as he texted me few days before saying me that they had fight between them and he wants a revenge. now the pics are real as all of them are selfies and my wife's expression clearly depicts that all this is done with her consent and support which proves her cheater. because he was called home only the time when no one is at home clearly depicts that she is too involved in it and had a smiling and happy expression on her face in pics. so now i want divorce fom her but as she is pregnant right now but now my question is i have a doubt about this child is mine or not. so can i refuse to take its custody or can i ask for a medical test before accepting the custody. as i got this pics i have called up my parent in laws to discuss about this matter but they refused to arrive. after several time calling up they sent her elder brother. and we discussed all about this and asked for a mutual divorce. now they are asking me to grant one month of time. so please guide me should i grant them the time or should i go for filing the divorce petition in court. should i have to hide or reveal the identity of informer who had send me the pics as he is my wife's boyfriend. is there any punishment for this which i can ask to the court for cheating on me and ruining my life.