do I continue to live the lie and let her go behind my back while were married? Or be a man and ask for the truth?
First of all I'm very sorry, that is a horrible discovery.
You are not "letting her go behind your back" because she does not need your permission to do so, that is her choice and she owns it.
WRT your question, you can be a man and not confront her. Play it out -- what are you expecting to happen when you confront her? Are you expecting an apology? A show of remorse? Compassion for how you feel? Surprise and sadness that she's been discovered?
That's usually how people go into a confrontation, they usually get none of those things, then feel even worse because the cheater makes them feel like they don't matter at all.
Confrontation is a personal decision, just ask yourself what it will accomplish and check your expectations going into it. The most likely reaction you will
Married 18, Together 20, Now Divorced M: 48, W: 50, D: 18, S: 16, D: 12 Bomb Dropped (EA, D): 7/13/11 Start Reconcile: 8/15/11 Bomb Dropped (EA, D): 5/1/2014 (Divorced) In a New Relationship: 3/2015