Hi Jen. Welcome to the forums, one of the best places to be in the hardest of times
I think you found a lot of the things you already needed to figure out. It sounds like space and time is the thing you really need to give right now, along with patience. That doesn't mean you have to "let" him have an affair. To the contrary, I don't think that will help in the least. But how you approach is very important right? Listening. Caring. Patient. I think that's the right approach based on what you said so far.
Keep your chin up. None of us are perfect, but striving to be better is what sets us apart from the mushrooms...
AJ
"Our lives begin to end the day we become silent about things that matter" MLK Put the glass down... "Yesterday I was clever so I wanted to change the world Today I am wise, so I am changing myself."