Stick a fork in it! It's done! Make divorce arrangements.
I believe on should give their all in a marriage and if my all was not "enough" then there is nothing else I have left to offer. Move on!
Each of us is entitled to (have our own) "deal breakers".
Over the years I've come to learn that there is no such thing as a "universal" deal breaker. Whatever you or I could come up with there is someone who is leaving under those conditions who has absolutely no plans of leaving! Cheating is not a deal breaker for some folks.
Another lesson I've observed is there is a big difference between the "hypothetical" and "life".
I can't tell you how many times folks have proclaim that cheating is a "deal breaker" and yet when they bust their mate they stick with her or him. I've heard of men knowingly raising a child by "the other man"!
I've seen guys on shows like "Paternity Court" or "The Maury Povich Show" AKA: "You are NOT the father!" sit there crying vowing to continue to take care of children no matter what the DNA outcome is.
My guess is if they were posed the "hypothetical question" before it happened in real life they most likely would have said "No way!"
"Never love anyone who treats you like you're ordinary."
- Oscar Wilde
Being cheated on or betrayed is never good but for your spouse to actually bring someone else (under your roof and into your personal bed) says a whole lot about how they feel about you.
You're nobody "special".