Lost and Hoping:
I know you're devastated, but it's not over. It's just over for now. I've seen people re-marry after divorce. But I'd like to offer a different perspective on a couple points as you continue your self-reconciliation for the time being.
a) It's not over until he's engaged or married to someone else. Until then, keep climbing uphill and you may see him at the top.
b) It's possible he will or even has forgiven you, but forgiving you doesn't necessarily equate to wanting to be with you. I think there's an important distinction to be made here. Just a thought to consider.
c) In my experience, it wasn't that I couldn't forgive my fiance, it was actually I couldn't get past 3 things, all of which fell under the betrayal umbrella and played a huge part in my decision to end the engagement.
Your description of your husband's experience resembled mines, so I'm sharing with you a couple of contributing factors weighig into my decision.
1. The physical affair. Of course quite painful and penetrating, but you already know this. No need to elaborate.
2. The indecent and disrespectful means you treated your husband (your description) while in the affair is what I recall as being as hurtful and demeaning as the physical aspect. It's one thing to dishonor the relationship and another to disrespect the individual. It was like a double betrayal.
It's one thing to lose a relationship and another to help a person lose him/herself which is how one feels when treated unkind, unpleasant and unworthy of human decency. I'm still aquaintances with my fiance but two decades later, I wouldn't consider her as a mate because I saw the lack of decency she was capble of delivering and I wouldn't risk being treated like that again.
3) You mentioned it was around your father's death when you saw the difference between your AP and husband. In my experience their was a similar circumstance that enabled my fiance to see things differently. What's interesting is my fiance shared with me the differences between me and her AP thinking I would be impressed with being better in her eyes, but it was the exact opposite for me.
If I'm your husband I would be thinking if your dad didn't get ill, you'd still be with AP and still treating me as if was unworthy to stand in the same room as you. While you can respond by saying you would have eventually realized this, it would come across as self serving and self depracating in hopes to reverse the previous wrongs.
It's possible the clarity you achieved could have occurred 2, 3 or 4 years later....or never. For me personally, I didn't want to chance my future with my fiance since her change of mind was caused by circumstances and not necessarily during a normal period of inner reflection.
I'm sharing this so that you can gain a possible deeper perspective. Not being able to get past it were my exact words because that's what I felt and the three issues cited were the ones I couldn't get past, specifically.
Like him, it took me over a year to reach the finality of our engagement to occur. Like you and your husband, I straddled the fence for a while, but was always strongly leaning to break it off. I felt my fiance was sincere, but I could not get past the 3 areas cited above.
So, if you haven't discussed your mistreatment of him or the enlightenment caused by your father's death, then consider discussing it with him if you haven't done so already. Discussion may lead to a deeper sense of remorse, which is a necessity for him to move forward with you one day.
Lastly, and it's related to my first comment. Not being able to get past something can also be read as him saying, I can't or won't respect myself if I reconcile with her. If this is the case, then he has to divorce you in order to restore his self respect.
Divorce can lead to the retun of his respect and dignity, and thereby open a pathway to reconsidering you once again. So, prioritize his recovery and provide him with what he needs to heal and if his heart is softened, you may still have a chance after the divorce.