Need advice from people who have been in this situation:one cheated then other got back at you> Now what?

TIt for tat, is that the game being played? You cheat so he cheats and you live happily ever after? If you love this guy and he loves you, then go to marriage counseling before any more love and and try to get your heads on straight about what is important, how to set and respect boundaries in marriage, and how to communicate with each other fair and square. Do it. It will help. Good luck.