Still think you should wait for someone wiser than I, but thinking about this more, I think the correct response here is something along the lines of, "I don't think there's anything to talk about as long as you're still talking to OM."
She doesn't need to know how you know this. When she lies about it, you don't have to prove she's wrong. Don't FIGHT about that. But don't let yourself be in an open marriage, unless that's what you want.
If she wants to D, you can't stop it. But you also don't have to have long conversations about it, either. Let her do the work on it. It sounds like she really doesn't want to go through the effort and needs to convince herself to do so. Don't give her the means to do that. Be a strong, happy, active, non-codependent chris19. Be a husband only a completely fool would leave.