I think coming to terms regarding the original A is important. Figuring out why, having transparency, rebuilding trust, and forgiving...all necessary to moving forward. At this point, he may not be willing to participate, but a lot of this you can work on yourself.
My W had an EA about 6-7 years ago. I was distraught and she had a lot of guilt...we discussed the hurt, and decided to push forward. But we didn't do any of the things I mentioned above...so fast forward a few years, and it happened again. If anything, I think my additional lack of trust in her pushed her away and towards someone else faster than before.
How about that list I posted? What do you want to work on for you?
