I'm In Trouble Now. I Didn't Look Away....

Last Sunday night, the night after our big 4th of July party on the lake the only hold overs at the cabin were my wife and I and her older sister Katy and Katy's husband. That night, after they had been drinking all day they wanted to go out on the lake and watch the locals shoot off fireworks. So we all got on the pontoon boat and went to a secluded part of the lake with minimal lights to watch. Around 11:30 we were about to head back to shore and Katy says we should go swimming. Before anyone even agreed she stripped naked and jumped in. Her husband was hooting and hollering like a drunk fool for a minute and then did the same.
I was just sitting there enjoying the show when I felt the stare from the wife. I looked over and she says, what are you looking at! In my mind I thought, your sisters tits and shaved pussy, but what came out was, are we going to join them? At that point they must've sensedy wife's disgust and quickly climbed back on the boat and got dressed.
Been nearly a week and my wife is still pissed that I eyeballed her naked sister. I could maybe understand if her sister was hotter or younger than her, but theyre about equally attractive. Seems like a dumb thing to be so pissed about, but I guess I shouldn't be surprised, my wife is always jealous of every female I've ever come in contact with.