In my situation, after her affair was over, my wife took a position of, "I'm sorry I hurt you, but I'm not sorry I had the affair." When I asked her if she felt remorse, or it the affair was a mistake or wrong, she said, "No. I don't need your forgiveness, because I didn't do anything wrong."
OK then...
Why didn't you tell your parents or the children?
Why didn't you tell the world at large?
Why have you only confided in people who were permission givers and who would support your decision to cheat (actualize yourself)?
Good question. Perhaps it's inconvenient to share the affair, since infidelity is still largely frowed upon. Who wants to be thought of as an adulterer? It's still socially unacceptable.
On the other hand. Everything we do should be able to stand in the light of day. If it can't then, that should tell us it's wrong.
If we are putting our needs above that of our family, then it's easier to lie/conceal the affair, and hope that it all comes out in wash in the next 5 yrs when everyone accepts the new situation and the "lovely" blended families created by infidelity.
Maybe it's the same reason people ignore the facts about the effects of divorce on children.
