I think people have to come to a point where they can accept one another. You have to accept what he did, and he has to accept the ugliness of the rage and pain you feel; you both have to accept that you are deeply flawed creatures.
The marriages I know well which have lasted for 20+ years are all complicated and all have serious challenges built into them.
I think that having a long relationship with one person you love, and have created a life with, can give you an opportunity to keep confronting yourself and growing: addressing whatever the most central problem of your psyche actually is. Perhaps your husband's affair has shattered your romantic narrative of what life should be like, and you are having to confront the fact that life can be messy, complicated, mundane, ugly, and meaningless at times, (as well as beautiful and joyful). Perhaps his affair destroyed not just your illusions about him but your illusions about your own place on the earth.
You know when you have a sore spot on your body, or an irritated finger nail or something, how you always want to keep going it to see if it still hurts? It is hard to just accept that yes that spot is painful and no amount of prodding will make it feel better. Then one day it is less sore.
Esther Perel has a few good things to say about recovering from problems, especially infidelity, in a marriage. She says that everyone will get married a few times over the course of a lifetime, but for some people all of those marriages will be to the same person. I don't think it is possible to go back to the marriage you used to have, but it may be possible to have a second marriage to your husband, and that marriage may even be better than the first in many ways, with more understanding, more depth, more commitment.
You seem like a very thoughtful person, and it sounds like you have a great deal of love for your husband, and he for you. I think that working through all of life's difficulties together is incredibly romantic, and I hope that you find peace and acceptance, as well as joy and romance in your marriage.