You have to set some boundaries or she will walk all over you and lose respect for you. Will you accept an affair on the bases she may not seek D? This is up to you. Personally, I would tell my wife that dating other men while married to me will not be tolerated. If she has an affair and refused to end it, I would then cut off all the benefits I could of being my wife. I would not allow her to come and go in our house as she pleases. Set up a schedule or call first. She chose to leave you and move into her own place, remember? I would not seek a D though… Just sit back and see what happens for a while.
It’s funny how often the grass isn’t always greener on the other side after all.
M: A really long time. Crisis: 5 years. She's still worth it.
Life is never made unbearable by circumstances, but only by lack of meaning and purpose. -Viktor Frankl