Although my sitch is different, I was married and divorced before (that one was annulled too). Even when it seems like the right thing, the only thing left to do... it is still a death of sorts. You think you have made peace. Like when a loved one dies and a critical anniversary, birthday or event happens... it breaks you a little again. You have to grieve again. You miss things again. I don't know that if you truly love someone enough to commit your life to them that you can really just let it all go when it looks like the end is truly near. You must still stir the ashes a little.
In this case, looking at the old memories as you mentioned earlier. You may need to look at them again. Feel both the good and bad of them and then forgive. I always knew forgiveness happens in phases. Things come up, we need to forgive again. You seem so strong from what I've read about your sitch.
You will get through this. Love never dies. It changes form, it changes shape and if we let it... it changes us for the better. I hope that you find peace as you go through this. I hope that you continue to cherish you and the changes you've made...
You will get through this. I tell you this, as I tell myself. I am deep in this still with my H. Not willing to give up, but willing to let go and let God.
Blessings
W (me): 50 H: 46 M: 21 T: 25 S:17 D:15 BD 11/2019
Fate whispers to the warrior, "You can not withstand the storm" And the warrior whispers back, "I am the storm." ~Unknown