I know that I should treat him like I want to be treated before I decide to leave him. Why can't I bring myself to do that? The hurt he has caused makes me even more hard-hearted. I just cannot picture myself ever opening my heart up to him again. I am so angry that he has not tried to 'win me back' or show me that he is sorry. The last time we had a fight about it and I told him I was not sure I could stay married to him, his answer was....it just takes time. No, I am so sorry, I love you and want to make it work, just that it would take time.
The reason you can't bring youself to treat him in a positive way is you want to punish him for what he did.
The positive thing for him about you treating him poorly... if you do decide to divorce him he will regret losing the marriage less because he will think of you as angry, unable to forgive and unhappy. That's the memory he will have of the marriage.... Any other woman will seem like an improvement. He will have more of a chance to find someone who loves and accepts him exactly as he.
He's right about it taking time. Also, too much damage has occured, you cannot stay in this situation having expectations.... you have to start slow, expect little, and just try and work on developing a friendship first.
There is no arriving, ever. It is all a continual becoming.