Speaking on behalf of all the good
WOMEN in this forum

...If I was that deeply in love with my man, I wouldn't have messed around in the first place. However, to play along with your scenario, I would definitely NOT tell. What he doesn't know, won't hurt him. If I would be that bold to cheat...I would think I would have the sense enough to do it so discreetly that no one, other than myself and my boy toy

, would know about it. So, I wouldn't be paranoid...walking around thinking someone else is going to tell him because no one else would know

. As terrible as this may sound, I would probably take the little affair/incident to my grave.
By the way I'm aware that everything done in the dark must come to light eventually...but I still would take my chances and refrain from telling him.