This it what happens when you put yourself in precarious positions with men that are not your husband and women that are not your wife. That's why its a good idea to not find yourself in those positions. Shit happens people, it particularly happens when that legal drug called alcohol is involved. Know it and form relationship boundaries that you and your spouse have agreed not to cross... make the first one that you'll not find yourself one on one with a member of the opposite sex in an erotic setting... like a hot tub for instance.
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BTW, OP: I find it interesting that you dragged him out of the hot tub and punched him rather then asking your wife to explain HER action there and then.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion