Watching my wife get fuckec by my best friend [MF]

My wife and I have always talked a little about how much it turns me on to think about her getting fucked. She’s pretty shy and somewhat reserved generally, but can be a lot of fun in the bedroom. She’s gorgeous and frankly out of my league. She’s 5’5”, 120lbs, blonde, fair skin with a few freckles, Irish heritage, gorgeous green eyes, B cups with amazing pink nipples, the tighest little pussy I’ve ever been in which she normally keeps bald shaved. We’ll call her Sherry. My best friend, we’ll call Kirk. They flirt a bit, mostly harmless stuff. He’s a nice looking guy, well built, never has trouble with the ladies. I jokingly encouraged them to flirt for a while and would always grab her phone when she wasn’t around to see what they say. Anything that would be even remotely flirtacious would end up with me jacking off furiously. Drives me crazy.