Personally I don't think I ever could get past it.
I'm too much of a "visual" person. Much like someone breaking into your home I'd feel like the marriage has been violated.
None-the-less there have been some high profile marriages that remained in tact such as the Clintons and Kennedys after it was apparent the husbands cheated. I can't think of any situation where the husband stayed once he knew the wife cheated.
It may be slightly easier if one is able to say they knowingly neglected the marriage such as (refused to have sex with their mate for several weeks) or was constantly berating them and taking their spouse for granted. Most unhappily married men aren't going to run down to the court house to file for divorce because their wife won't have sex with them. Under those circumstances it would take very little for stranger to put a smile on their face or in their heart. Everyone wants to feel desired.
However even mistresses are warned by their friends that "Married men never leave the wife" (on their own). This implies a unhappy husband is likely to cheat rather than end his marriage. A fact worth keeping in mind.
Either way it takes a long time to rebuild trust. (I suspect wanting to forgive is also tied to the shock of finding out). Sometimes it's too much to take in finding out your spouse cheated and ending the marriage all at one time. The betrayed person offers forgiveness as a reflex. They aren't ready to deal with a divorce.
My guess is quite a few people realize later on they can't forgive even if their husband/wife is doing everything possible to mend the marriage and earn their trust. It's probably best to take a couple of weeks apart to determine if you "really" can or want to forgive. If you decide to forgive it's not fair to contantly bring up the affair every time you have an argument.