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.
Remember, no one lives a charmed life, even though it may seem that way. Everyone gets something and some get more.
So if a failure has hurt your heart and stopped you from moving forward, maybe it's time to let it go. Don't keep focusing on what you can't change; focus on what you want.
Have a nice day.