I would be devastated and make his life a living he!!......
I would be devastated, but it was only once and years ago, I'd try to let it go, so I could move on with my life, whether I chose to try to salvage the relationship or not.
We forgive people, not because they deserve it or because we condone what they did, but so we can continue on with our own lives in peace.
When I was working really hard to have a baby and it was not going very well, I told my husband that he COULD have an affair as long as I got the resulting baby. ha. AT least we can joke about those things which is a good sign that it hasn't really happened.
What I think cheating does is ruin our innocence of the other person. You can't really ever look at them the same way. Which is hard on a marriage because that is sad.
If it happened early on and things were going fine in our relationship now, then I'd be more inclined to forgive them.
but what would matter most to me is contrition. How sorry is he? If he doesn't seem genuinely sorry, then it would be too big of a burn to ignore.
And I'd also need room to make him suffer for it for a while. :>)
As to me cheating? Who has the energy for that?
I would hope to see the silver lining, and consider... Yes he cheated, but he still came home at the end of the day, hopefully because home is where his heart was. What to do with a man that follows lust down the lane? It would matter a great deal to me as ell, whether i truly felt that he was sorry and feeling true guilt all of the years in between. For instance, If i heard that he cheated once, and felt so guilty afterward that he never considered doing it again, I would forgive him (after the initial shock and no doubt yelling match). In fact, I hate to admit that this happened in my now relationship way back when we first got together. I was working 12 hour shifts back to back for months on end, with no day off. I had injured my back to the point i coudln't walk for 6 months during that first year (back injuries don't go away in my case and many cases.) . Yes, my man cheated, but he felt so guilty about it, that he had a nervous breakdown (within the week of his indiscretion) and had to be hospitalized for about 30 days in the psychiatric ward. He had also relapsed (drank) when he made the decision, (no excuse) and after the psychiatric ward went directly into a residential 90 day Relapse Prevention Program. He proved that he was sorry and willing to go to any lengths to prove he really meant that he was sorry. I love him death. I would have truly missed his unique qualities and nature. I feel very blessed to have him in my life as my partner. He's an incredible guy. I'm glad i didn't throw out the baby with the bath water and was able to read true contrition.
I have learned thru tons of counseling and my recovery that cheating really has nothing to do with the other person. It is all about us. I was a huge cheater back in the day. My self esteem was so bad that i thought if some other man was interested in me i was okay. It was that instant gratification thing. Afterwards it left me even lower. My husband is the only one i never cheated with. I am not proud of what i have done in the past but i have learned some very valuable lessons which i am very grateful for.