I know you want to personalize your W's behavior as directly tied to your success of failure in DBing. I totally agree with Sage when she told you:
Don't think this is trite but your w's behavior has NOTHING to do with you and your DB success. It has everything to do with her. There is NOTHING in your post to indicate "fraud" or "failure".
It also sounds like you are now doubting your own perceptions and judgment (i.e. you thought things were improving greatly, but now think it was all a "lie".)
I would tend to disagree. I am not at all condoning your wife's behaviour, but it also doesn't sound to me like she is insincere about her love for you and desire to work on your M. It sounds to me like she is operating in some duality of thinking, compartmentalizing the visits with OG, and not seeing that it could or would have any affect on you or your M.
Still, I totally understand your feeling the need to give an ultimatum. I think the secrecy is very damaging, but again--she likely is compartmentalizing the whole issue.
No 2x4 from me about snooping. I am one of the few here who really believe I have the right to know if I'm being lied to or betrayed. I like to make my decisions based on fact and you know the quote: "trust but verify". So if you're getting 2x4's, I'm sure I will too.
Unfortunately, snooping can become an obsessive thing, and if someone knows you're snooping, it only teaches them to be better at hiding they really want to hide something. That's the downside. BTW, how DID you explain what you found out to your W?
OG lied to you of course, but have you considered that he lied to try to protect your relationship with her rather than trying to protect his relationship with her?
I understand your fear that OG may sabotage you now that you've clearly drawn your line in the sand. I think it's far more likely that he may panic that take advantage of the situation. Remember the fantasy aspect of A's. Do you honestly think he wants her showing up at his door one day with 2 kids and expecting him to step up to the plate because he contributed to causing your M to end? I highly doubt it, he'd probably turn tail and RUN.
As sad as I am for you, I don't think you're failing at DBing or should give up hope.