So this week in my Chemistry class I learnt that there is no such thing as an irreversible reaction.
This blew my mind- I knew that you could melt an ice cube into water, and then freeze it again for it to become ice as a reversible reaction, but my teachers had always taught me that if you toast some bread you can't turn it back into the bread.
Well, it turns out that was all a lie. You can bread toast, if you put it through a rather advanced series of chemical processes that would likely cost an awful lot of money, energy and time (which is why we don't use them!)

I see this as being the same for mistakes. We've all made bad decisions in our lives, but none of them are irreversible. No mistake will scar forever if you are willing to put the time and effort into it, just like the bread.
I have realized that there is no need to have anxiety and stress over your decisions, as you can change them, they are not final, they do not define you!
People do, and will always forgive and forget.