Cheating bf? what would you do ?

So I just found out my bf has one of those zoosk acts I broke in his email what should I do how do I approach it im so pissed he's been LIEING to me I want to approach him but kinda wanna play it a little but what would you do also were pretty serious we have a four year old and were trying for another we just moved outta state and I have no one here with me