I can understand how torn you must be feeling!
In Nov last year we moved to the city where my fWH had the A. I hate living near all the reminders, all the triggery places and worst of all.....10 mins drive from OW's house, where the A happened. I hate it. But there are good reasons for us being here, so - like you have had to - I suck it up.
Seems to me that your life is going through seasons. You've had the season of living in "hell" and having the great MC and now it's time to move into a different season - one where you don't have to live in "hell" (lucky you!) but where your more mature marriage has to cope without your MC. Just reading what you have written and knowing that you have had so much time building on your marriage with this brilliant MC, I feel such confidence that you will do fine.