My wife cheated and left with one of our 2 kids, what should I do here?

I had an affair behind my wife's back, while she stayed home with the kids.At least, I thought so. She had a boyfriend whom she hung out with. She slept with him. She also had flings with her exes and even a friend of mine. I caught my wife in bed with her boyfriend, and I got angry at her. Yet, she became angry at me for sleeping with my girlfriend [19F]. She called me a cheating pig and a creepy old guy (since my girlfriend is 19F), despite having a boyfriend and messing with him.She and I seperated, and she took one of the kids with him into her boyfriend's house. I got one of the kids with me and my girlfriend in my house.What can I do to get her to leave her boyfriend and come back with me?TL;DR : Wife seperated from me for having an affair with girlfriend, yet she has a boyfriend. What do I do now? She took one of the kids. via /r/Parenting http://ift.tt/2xNcB1E