you can't go back in time.
You can't unmarry, you can only divorce.
You say you're happy in your relationship as it is now, and don't want to split up.
What's in the past, ie. your marriage being a lie, is in the past and you can't change it. You can only work with the situation you are in now.
You have children together, and presumably you both want to make your relationship work. Do you really want to put your children through a divorce and then another marriage just for your own sense of it 'feeling right'? It seems a huge length to go to when the only difference between you two and an umarried couple is a piece of paper.
I think you have to try and come to terms with the past, the decision you both made, and how things have subsequently changed between you.
I think many many people probably get married each year who don't entirely mean their vows. Some of them divorce because they no longer want to be together, and some of them make it work, as to all intents and purposes it sounds like you have done.
I think it is up to you to try and change your perspective on this. Stop looking at how the past wasnt perfect, and try to see how your present circumstance, in the here and now, is actually pretty good.
If you divorce your husband, you won't go back to where you were before you married, it would be unchartered territory as ex-h and wife, and who's to say that would suit your any better than the way things are at the moment?