Cheaters Anonymous Community Group
This is a support group for cheating spouses looking for understanding and strength. Betrayed spouses are welcome to post ONLY if they can do so in a supportive manner (no bashing...these posts will be deleted), and please do not comment on 'Cheaters Only' posts.

I think you can get through this with your marriage in tact. I think that the obvious first step is distance from all parties involved. Phase them out. The kids being friends is an issue but unless you're ready to blow the whole thing wide open you're going to have to be ready to compartmentalize that aspect. It doesn't mean YOU have to stay close to the family (I imagine your kids are older and don't need you to facilitate the friendship).
A) You confessing to the A and showing real remorse, coming clean and being honest with him.
or
B) Your H finding out about the A from the AP's W, getting to hear her account of it first, and then having to confront you.
Having been on the receiving end of something similar.....I would definitely go with A, because to me, discovery is more damaging to trust than confession. But then again, each person is different.
Just food for thought.