I watched my wife get fucked the day before we married also, but never told her. I knew she was still getting fucked by other men while we were engaged, and she knew I knew. But when you consider that I knew when we met that she was a but of a slut, and she even admitted it, it was just a matter of time before she would become a shared wife. She also knew I was a voyeur.
Anyway..... the night before we married, (and I say married because it was no fancy wedding, just a Justice of The Peace) a car pulls into our driveway and I figure it's my soon to be wife home from her last night out with the girls. But after a few minutes I realize that she hasn't come in the apartment yet. So I go look out the upstairs window and the motion detector lights are on and shining right in the windshield of a car I recognize as belonging to her sisters ex-husband. I have a clear view of a white ass pumping between a womans legs in the reclined passenger seat. I couldn't see who the woman was but since it's my driveway I can only assume it's my soon to be wife.
What I saw was in no way love making. It was flat out fucking. I knew he had fucked her a few times before we met because she told me he had, but I had no idea he still was. He was pumping her like a 2 dollar whore. I watched until he finished and rolled off and I could see it really was her. I slipped back into bed and never said a word to her about it. Even 7 months later, when I caught her fucking an old boyfriend and she confessed about the ex-brother-in-law, I didn't tell.