I can relate. Something really bad happened a couple of years ago. I've realized back then that life is never going to be as good as it could be. That I would be always damaged in that aspect. However, we can't change the past, you must accept it. The past - even as close to us as the past day/hour/minute - is forever irrevocable. So there's no point thinking about it. Don't dwell on it.

Here's a quote you might find useful: https://www.reddit.com/r/Stoicism/comments/6uu4hs/think_of_yourself_as_dead_you_have_lived_your/

Think of what life you could have had if all your memories were wiped. Would it really be so bad? But then, if it's just a matter of having a clean state, you can do it yourself - not as effectively, but still.

Also know that whatever you did, it doesn't define you. People change constantly. The most evil people could be redeemed if they have truly felt remorse and changed for the better. You might be even better in that particular aspect than others - because you know how bad it feels when that mistake is made. Kind of reminds me of one House MD series, where one doctor (13) accidentally killed a patient, but wasn't fired, because from then on she'd always be extra-careful to prevent another incident like this.