Unsure if the sister-in-law really knows but perhaps has guessed.....
Wife’s sisters husband passed away and she was somewhat reluctant to get back into some action. She wanted too but she is a bit prim and proper (rather different to my wife
) and needed some encouragement to make the first step.
She came on holiday with wife and I and we sort of planned a meetup at a bar near where we were staying. Long story short, I flaked out pretending I wasn’t feeling well to give the girls some room. They hit it off with a couple of guys and sis was definitely interested and felt more confident with wife around. Don’t think the wife was really looking for any action that night, was focusing on getting her sister back in the saddle.
However it turned out the 2 guys were staying in the same apartment and sis was not comfortable going back with 2 of them by herself, so wife had to tag along. All the while I was getting updates on progress
So wife and sis ended up getting banged by these 2 guys (seperately) and staying the night. Next morning a bit of realisation set in and sis was feeling a bit embarrassed, so I got messages from wife saying stay in bed, pretend you are asleep….girls sneak in around 9 and catch some sleep (wife later told me sis definitely made best use of her time that morning
) .
Early afternoon we catch up and I have to pretend I didn’t hear them come in and they have to pretend they got home around 3am.
So sis definitely knows I am technically a cockold as she knows the wife fucked another guy but she hasn’t been too keen to ask more if it was a one-off or a more regular occurrence, though I suspect she has guessed.