I've done irredeemable things.
I'm sure that you can be forgiven for what you've done.
You can't understand that. You don't even know what has happened to me.
It's good that you recognize the harm you might have committed with any of your actions in the past.  You can help to fix any damage you have caused, and people will be willing to forgive you in time.
I'll never feel the same way again.
You can still make it up to people from what you've done in the past and redeem yourself. How does that saying go, "every saint has a past and every sinner has a future".