Without "her" finding out? Or Without "her" husband or anybody else finding out? Major difference. For the 1st one, she'd have to be on some kind of date r..e drug or blacked out drunk or something of the sort. For the latter, all that's required is for everyone involved to keep their mouths shut.
No Drugs - No Drink needed just plain old barebacking the slut from behind whilst 1 or 2 guys keep her mouth and hands busy. It will also be good not to cum inside her which would be a giveaway to her that she is being barebacked lol!
Save the cum for her face. The risk of not being caught makes it more exciting would you agree?