The going dark thing is a reference to where members here simply leave their spouse unannounced for days or weeks. This shows the spouse that they are done with the marriage and gives the spouse a chance to miss them.
I dont think thats what it means. Its just cutting all contact and stopping any communication with spouse. In your case since you are in the same house it is difficult I guess. it would work well if you are living in separate places. I do not think leaving unannounced would be the correct way because it is supoose to be done respectfully. Leaving unannounced would be rude. I think you are in denial and not really ready to put boundaries or ask her to leave or respect you. For her life is normal and she can still have benefits of your presence and bills you take care of and go astray. If she loses those and arrangements change she may wake up and make a decision.
M 11 Dated for 4 years before then Me 35 H 39 D 10 BD Feb 2016 A 2015 Dec I was never in a R with the OM. Had a one night stand & I stopped contact immediately I confessed the A to H and we went for MC