That's awesome Jake! You are super lucky. As you can probably tell by the advice you're getting the situation is often much worse. The fact that your W is willing to discuss this with the MC and admit what she has done is a betrayal speaks very well for her.
Did you discuss the fact with the MC that you don't believe what she's telling you? It sounds like she's saying it was like a big episode of "Three's Company" where everything is a double entendre taken out of context.
If you don't believe her and this continues to eat away at you, it becomes another elephant in the room, so maybe you do want to discuss at your next MC session. A word of warning that you may at some point get an ultimatum from your W that you need to stop questioning and "get with the program". No one likes to feel doubted forever. When she makes that ultimatum, you don't NEED to accept it. Just think about how you might handle it.
With regard to trying to compete with OM, that's generally not a good idea. Your goal should be to stop thinking about OM at all and think about your marriage. For most of us, we *can't* compete with OM.
-- OM is "new and different", we are the well-worn shoe, that while comfortable, may not be that interesting -- OM has no baggage -- you have all your prior hurts and relationship issues -- OM has no built in issues to deal with -- no in-laws, no shared bills, no parenting issues -- OM has no shared chores or other responsibilities -- no reason to feel resentful if the garbage isn't taken out, etc.
Jake, you have all those things, and you have also "trained" W how to think about you and how to interact with you over the course of your marriage. Even though you will make improvements and change your approach to things, the synapses in W's brain from years of conditioning are well-established. It takes time to remap your relationship.
The bottom line is that trying to compete with OM will only lead to frustration and feelings of inadequacy.
I had the misfortune in my snooping to read weeks worth of correspondence between W and OM. She had NEVER been that loving with me over the course of our marriage and that made me feel like cr@p. Eventually it lead to jealousy.
I still don't get that affection, and I never will, because a 17 year relationship will never be like a 6 month affair.
Save yourself the angst and don't go there!
Accuray
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