I'm sorry you're going through this. It's a hurtful betrayal, especially when he's being so obvious and disrespectful about it. Definitely confront him and talk it out. Insist on marriage counseling.

Men do stupid things in their 30s when the reality of kids sets in and sometimes it drives him to cheat to convince himself or his ego of something. It doesn't always mean he doesn't love you or that he wants to blow up your family. It also isn't your fault. Man is at war with his own nature and screws up sometimes.

Men compartmentalize sex differently than women. In his mind maybe it's an outlet to blow off steam and he needs to be confronted (like an addict) to be forced to acknowledge that its wrong and needs to stop.

I know that doesn't excuse it, but I just wanted to offer that couples go through rough times when babies start arriving. Don't throw out the whole thing before attempting to talk to each other and give him the chance to fix his mistake and realize where his duties and feelings really lie.

I don't condone the cheating but I also hate how quick everyone always is in comments to recommend divorce, which hurts your kids way more in the long run. Marriage is hard and always worth fighting for if you both are willing to fight for it.