Any chance your wife is getting pressure from the OM? How do you know she went to see the OM or went to talk on the phone with him? You seem a little vague there, which may mean you don't have hard proof of anything. I can understand, as my mind sometimes wanders to worse case scenarios when I am trying to piece together my wife's stated whereabouts, but I'm always wrong so I try not to do it.
The "open relationship" comment from your W tips her hand on what seems like an aversion to getting divorced. Just an example of the crazy stuff that can come out of the mouths of those in affairs. But it seems like she is not completely done with you, or why wouldn't she jump at the chance to get divorced? What is she waiting for?
All I can say is my attitude was much like yours in that I said "dump the OM or divorce me" but my W always waffled at that point, and has not filed or even seen a lawyer. I agree it is no way to live, and I had her leave rather than sit on the fence. But I'm not willing to file as I still hold out hope of saving my marriage and realize the road may be a really long one in my situation. But I have detached, don't respond to any emails or texts that don't require a response, and don't call her for any reason other than family business. The weird thing is that my W reaches out to me, and this is from a woman who has said point blank she has no hope for us as a couple.
The question is do you have hope? If so, maybe go ahead and separate and then detach. Don't concern yourself with what she is doing and go dark on her. Since you say you are willing to file, you always have that option if separation and detaching does no good.
WAW Using God Me-43 W-40 M-14 S-11 S-9 D-7 EABomb 5/09 Separated 12/09