Take a deep breath Stunned - Just because you want to try, doesn't mean that has to be set in stone. None of this is an all or none proposition for you.
Youe get to decide how to play this out. If your FWH hsa made it clear that he is willing to work, the Hoorah for you. That's a step closer than a lot of others get. If you want to give it a whirl then do it. Tell H that you are willing to try, but your requirements are ABCD, and think a long time about what those will be.
I found that mine were pretty simple. NO Lying, NO hiding, NO omitting the truth, NO CONTACT with OW ever. If he did any of the above I was done, and he'd be out the door. He also knew that my requirements were subject to change should I feel, or see a need for that.
We were a good 6 months into R before I was confident we would make it, 100%. It took him really working to fix what was broken within himself, and him being absolutely remorseful for me to get there. It took me well over a year to stop snooping. To have an inkling of trust again.
You will eventually get to a point where you don't need to ask questions, when you hear the same answers multiple times, and when you see his actions in the present differing so much from his actions during the A.
It took a full 2 years for me to feel like we had really come out of the shitstorm, healed, and fixed. I would say I think that was fast tracked.