Our youngest (17) at the time caught me sleeping on the couch one night while my wife's long time lover was "visiting". He started acting up a little. I asked him if he was upset about our friend (which he had known most of his life)? He said yes, so I explained to him that everything was fine, and that our friend, his mom and I were all very good friends and everything was fine and there were no problems between his mom and me. He calmed down after that. It was very ackward.
I'm sure he remembers my wife having "friends" come for "visits" and disappear into the bedroom for a while, and then go, since they were little. And then as they got older, a few times a year, my wife would be out of town for weekends, or even a couple days at a time during the week because I would take her to the airport to fly out to visit "friends".
Many years later he did a DNA test and acted excited about his heritage. Then he sent me a DNA test. When I got the results, he was very insistent that I send them to him, which proved I was his *******. I believe he knew his mom was a slut, which she was for most of our marriage, and suspected our friend was his *******, or at least that I wasn't his *******.
I don't know how much my youngest one knows, but I do know that when my wife and I separated, I asked my youngest (18 by then) if her mom was seeing anyone, and she described our friend perfectly to me, so I knew he was still fucking my wife, and my youngest knew then also.
What neither of the ******* know is that my youngest is from my wife's first affair about 3 years after we were married.
Neighbors knew about my wife's affairs, and some of my wife's friends (also neighbors) knew only because they'd heard rumors and seen guys visiting, but neither my wife nor I told anyone. My wife told me one friend of hers (next door) even confessed to cheating on her husband with a Black Guy, and tried to get my wife to confess, but she wouldn't. She just didn't feel it was any ones business, no matter with they saw.