You build on failure. You use it as a stepping stone. Close the door on the past. You don't try to forget the mistakes, but you don't dwell on it. You don't let it have any of your energy, or any of your time, or any of your space.
So, I learn from my mistakes. It's a very painful way to learn, but without pain, the old saying is, there's no gain. I found that to be true in my life. You miss a lot of opportunities by making mistakes, but that's part of it: knowing that you're not shut out forever, and that there's a goal you still can reach.
For you I know I'd even try to turn the tide.
How well I have learned that there is no fence to sit on between heaven and hell. There is a deep, wide gulf, a chasm, and in that chasm is no place for any man.
You've got to know your limitations. I don't know what your limitations are. I found out what mine were when I was twelve. I found out that there weren't too many limitations, if I did it my way.