Ruby, just read about what happened. I'm glad you've been able to turn this into a learning/awakening experience.
I found not one but many letters that Joe wrote about the OW and how he felt about me. I still remembered his words. He even wrote a poem to her and drew a flower (even though he's so not artistic.) Six months later, he had absolutely "no feelings for her." So that goes to show you.
But what matters is that you accept what is now. Your H feels the way he feels now, not the way he felt 10 years ago or the way he should feel. So acceptance is key.