A few years back I once sneaked on my b/f's (now husband) Facebook because I 'knew' something wasn't quite right. Confirmed my suspicions that he was heavily flirting with a woman at his old place of employment (they even got as far as making out). Not my finest hour but I'm glad I did it. In the end, I was the one who gave him the ultimatum. No more lies of that magnitude or we can't be together.
I think your wife's transgressions are far worse than yours. Why cheat if your relationship is open in the first place? My hubby sometimes has a hard time with being truthful if it means pissing me off or hurting my feelings. I forgive little white lies on occasion but never again will he attempt to cheat on me or he's out, that's clear. If he fancies someone, I want him to talk to me...not go behind my back. I need honesty if I'm going to trust him.
I tried being reasonable. I didn't like it. ~Clint Eastwood~