Mr. Marvie cheated on me about a year after we got married. It was a one time thing, and we actually have an open relationship (yes, you can 'cheat' in an open relationship), but the way everything went down afterwards was instrumental in saving our marriage - and our community.
He told me, I freaked out, went to work, wrote very angry things on the internet and listened to a lot of really angry abusive music and then took off to a friend's house for the weekend in my home town... still very angry, still thinking we should get divorced. Our friends came together as a group to hug me and ply me with drinks and tell me that he was a shit head... but also that they honestly thought that two of us were good together and that it was a mistake on his part, and that they thought we could and should work through it and they would be there to help. Meanwhile, the same friends called and went to visit Mr. Marvie and told him the same thing -- that he was an asshole who did something dumb, but that they believed we should stay together and were there to help and support us while we tried to come back from this.
Mr. Marvie stopped seeing and talking to the woman involved immediately. He made it a policy to have all communications above-board, so he'd talk on the phone in the room with me, and let me see his e-mail and texts if I asked. We talked really honestly about what happened and why -- that it was a spur of the moment thing, that it wasn't about something he wasn't getting in our relationship or my being ugly or bad in bed or something. We also talked about how I was horribly angry at him, and hurt, but that I didn't feel that way all the time... but needed to be able to express those feelings when they came up. For the next bunch of weeks sometimes things would be fine between us and sometimes I'd get upset and need to yell at him or talk to him for a while. I also was able to vent and yell and scream to friends who always, always supported me in being angry but also supported me in continuing the relationship. Gradually, the periods of being generally okay took over, normalcy returned and I forgave him for what had happened.
We were also in the middle of expensive and emotionally draining IVF procedures at that point. We made a mutual decision to get off that roller coaster, and I slowly was able to see that the meds and stress were driving us both crazy. We tried other options and got pregnant a year later, with a stronger marriage and a way lighter bank account. :) Strangely, we are both now still friends with the woman who was involved, with very few bad feelings in the mix. It was a thing that happened, now it's over, and life has moved on.