It might be good that you are thinking about this up until the day, it will give you a chance to get ready. Your H (one of the top ten hard ones to figure out) will not forget this day, might be moody before or after, but also will mourn the passing. Just like you, he can't turn off all the years you have together, no matter what he is doing now.
I hope you can decide what you want to do, who you want to see, and fill your day up however it makes you happy.
PS: I also think of us reconciling in the future, far future, but you are right. I think we need to learn how to shut that off.
