I haven't read your whole thread but your discovery of the PA hit me hard as I was in that boat a few short months ago.
When it was confirmed for me, I waited until I was calm and then approached my H. I calmly said, "I know about the PA. I want you to know that I love you and I will continue to choose this M IF you end this R, have NC and total transparency. If you are willing to do that, I will walk with you through forgiveness and healing and helping you sort out whatever happened that got you here. If you are not willing to do that, I will not be your friend. I will have some difficult decisions to make, including filing for D." I then left. A few hours later he came and asked to talk. I took us three weeks to talk things thru and for him to end R with OW. We are now piecing.
If you confront... make sure you are calm, sure of what you need, sure of your boundaries. Take care of yourself!
