Need divorce

Hi Sir I got married in Dec 2009 and now have a 2 year baby girl. For past few years, I found that my wife is in constant touch with a man who is also married and who lives in same city from which my wife belongs. When I asked her about, she just told me that he is just an ordinary friend and they talk only few times a month. But recently I found(when I spy-ed her phone) that she is talking around 10 times a day on daily basis(in my absense, when I used to be in office). She chat on whats app and deletes all call & chat logs to hide that from me. This is her daily routine. I have few proof of her chats. Her chats indicates that man is still her boy friend. And I suspect that they meets whenever my wife visits her mothers place. Now, on one hand, I have zero trust on my wife and want a divorce. On the other hand I also love my baby very much. I am in a fix what to do now. If I go for divorce, will I get the custody of my baby? Do I need to pay a regular compensation to my wife after divorce? What if my wife denies for it? Please suggest me the best solution. I will be very thankful to you