I would acknowledge two things:
That you are already having an emotional affair. If you've both expressed feelings now, the line has been crossed.
That if you've been feeling like this about another man for a year, you are currently unable to view your marriage or your feelings for your husband objectively.
I've never met one person with an emotional investment elsewhere who was able to be objective about their pre-existent relationship and there's no reason to suppose you're any different.
That's not to say there mightn't have been problems in your relationship beforehand, but it is saying that your relationship will have got even worse since you formed an attachment to the other man, even if it was only in your head until recently.
It's often very hard for women especially to be honest about their lustful feelings for men outside their sanctioned relationships because of patriarchical distaste for women having sexual feelings at all, so when women have affairs it is very important to peel through the layers of all that lifetime's conditioning that women only reach outside a relationship if their 'love' needs are not being met.
It's too pat to say this affair is a symptom of a bad marriage, because you had a variety of other choices for dealing with your unhappiness.
An affair is more accurately described as a symptom of you being unable to express your choices in an adult, assertive way.
Your husband might have left it too late and the truth is that nothing he could do now would make any difference because your feelings are invested elsewhere. It's actually very cruel to ask him to try to up his game when he doesn't know about your other relationship. He is doomed to fail unless you are honest about the other man.
I'd suggest no contact with the OM and some counselling on your own.