Blah, blah, blah. In other words, she wants her cake, and eat it too.
This is all just classic infidelity SCRIPT. It is her feelings towards OM that are driving all of this drivel, DMB. The way I see it, you got two choices: aggressively move to bust the affair, or go "Robx/Gucci" on her.
She wants the security of your marriage, and you, but separated. AND the freedom to do as she pleases. In other words, she wants you as what we call around here "Plan B." I guess you need to decide if you're OK with that.
Sorry to be so harsh. I've seen THOUSANDS of these things now, and it's getting to where I'm just going to call them as I see them. They're really all the same.