In trying to be a great dad, give yourself credit for your efforts and avoid berating yourself. It is a challenging role to be a successful parent and we can see ourselves as "failing" at times. As long as you believe that you are trying to do what you feel is best for your children and you are prepared to admit and improve upon your mistakes, then you are succeeding 100%. Give yourself praise and treats as well as your child. And always encourage, support and praise your partner in their parenting as well.
We all make mistakes and have regrets over our words and actions at times. However, self-absorption about past errors can lead to depression and achieves nothing positive. If you have done damage, move on - don't do more damage by living in regret.