Stop lying to your children. Stop covering for your wife. Never stand between an infidel and the consequences of their own actions.
If people ask what is going on with your wife, tell them the truth. She is the liar, you are supposed to be the sane and honest one in the family. Your children, grown or not, need someone they can trust.
All cheaters lie, why in the world would you want to help someone else screw your wife by covering for her?
Exposing her fantasy is the first, best step toward getting it stopped.
All the best, -NOPkins-
I will ferret out an affair at any opportunity.
-An affair is the embodiment of entitlement, fueled by resentment and lack of respect. -An infidel will remain unreachable so long as their sense of entitlement exceeds their ability to reason.