Is that shame necessary to guarantee your merits, though?

If you can still learn from it, then it still has a purpose. If everything is learned, then it doesn’t, and it is only hindering you. That call will be up to you, your understanding of the circumstances, and your conscience, but one thing is for sure: It makes no sense to worry about things that are outside of your control, and your past is very much among the things not in your control. So don’t fret about letting it be nothing to you.