My H confessed to me that he had a PA after it had been over for 3 months. One week later, he decided he needed to shed ALL his guilt and confessed that 13-14 years prior he had had a PA. I was rocking and reeling to be sure.
It was not for another 10 months that I would discover his ongoing long-distance EA with an "old family friend" whom he had not seen in over 30 years.
Oddly enough, when I found out about his EA I realized how deeply troubled my H was. I was able to see that he was not just a philandering son-of-a-bi*#h, but that he indeed in dire need of help.
My own father suffered from depression and took his own life when I was but 5 years old. He was never diagnosed with depression, as that was 45 years ago, but I have many letters he wrote my mother at that time and he was definately severely depressed.
I knew my H needed help -- at that point, he knew he needed help. He got that help and is now a completely different person.
But that does not negate the pain I felt/feel as a result of his betrayal. While intellectually I can understand somewhat of what he was going through, emotionally I am forever scarred.