I don't think the confrontation would be good. Odds are that her classmates would doubt your word and come to her defense.

I think it's one thing to out the adultery to people who can put pressure on the affair, it's quite another to embarrass your wife in public. Might as well go up and paint a red A on her chest.

It will backfire to do this.

Now, if you go and calmly talk to her in a public place in a voice only you and her can hear, that's a different story. You eliminate any ability of her to claim you're crazy and you accomplish your goal.

If things don't turn around keep your chin up. You are not at fault in any of this.

Learn from the experience and look for emotionally strong women down the road IF things don't turn around. If she does turn around, then approach with extreme caution.