I may take a different angle than many - but I suggest you take the emphasis off of forgiveness, and focus instead on healing yourself.
What allowed you to make the decision to cheat - and continue making it for the length of your affair? What was the mental gymnastic that you used to give yourself permission to destroy your husband and marriage? Work on fixing YOU.
You can't fix your husband, he has to do that. BUT what you can do is make yourself at least somewhat safe again - and become someone he might decide is worth the gamble of staying with. You have to win your way back into the marriage - just ending the affair (oops, sorry, my bad) isn't enough. Work on being the person you want to be.
It will help if you can find empathy. Can you imagine your husband's pain? You'll never really get the full extent of it, but TRY to see and feel the result of your actions through his eyes.
Forgiveness, if it ever comes, would be great. But IMO that isn't the real destination. A lot of people want to forgive and forget - that's NOT a good thing. Forgive maybe (if you earn it), but forget? Never - from a BH perspective, that would be a really dumb thing to do. A saying among the betrayed is: When someone shows you who they really are, PAY ATTENTION. You showed your BH who you are - now it's up to you to fix yourself so that behavior never repeats.