Every single one of us on this board could have been a better partner. It still blows my mind that out of all the useless courses they have in school/college that don't have anything to teach you how to be a better partner. Accept that you could have been better, learn from it and let it go.
What I think you should focus on with your ex is gaining respect from her. One thing that has always been obvious in your sitch is that she doesn't respect you. Once you can obtain respect, things will slowly change in the dynamic of your relationship.
