What do you think of me being a failure of a person for hoping my ex would come back even though I know he will never want me back?
That's not good. Are you always thinking about your ex?
I think about him when I feel bad about myself. I feel like he was the only person who saw me for what i truly am
You are not a failure, you are just in the process of grieving a break up. It is perfectly okay to be a little blue about this, but eventually you have to move on and find someone new to be with. Spending too much time on the past can let you miss the good things in the present.
I can't help it. I feel small and ugly. I want to go back to my old self and be loved again.
Well stop thinking of the past. You haven't failed yet, do your best to move on and don't stop until you have. You will only fail if you continue to think you are a failure.