Don't uninvite. Be the absolute best you possible, w/out being over the top. Then, don't be so hasty to invite in the future.

If you think he thinks you're ok with the A, and talks about it or the OW at all, be absolutely crystal clear that you will have nothing to do with that. Don't freak on him, but just make your position known. You will not be his sounding board about the A or the OW.

If/when it is all over, it may become time to talk about it, until then...you want to hear none of it.

My 2 cents.

Me: 34 W:33
T: 10 M: 6
S: 6 D: 5
BD: 5/14
Still together(ish)
Not giving up: 7/14
D talk has slowed, a lot.
Gradually working on things together. Still separate bedrooms.
Slow and Steady wins the race.