She has already chosen the OW -- she has already chosen to cheat on you.
Her movements toward you -- be they physical or emotional -- are cake-eating, pure and simple.
The best psychological frameworks I've seen for dealing with the sheer HELL that is infidelity, are the Stockdale Paradox (google it -- it's fantastic), and the Band of Brothers "I am already dead" paradigm. The sooner you can get to that place, intellectually and emotionally, the better you will be able to DB this thing.
You can find posts about "The Gandhi Approach" over on the Infidelity forum, I believe.
