I have been treating a lady for the past few weeks who was raped and is constantly beating herself up about why she chose to walk through the area that she did when it happened.  She keeps on saying that she wishes that she had decided to walk somewhere else that day.  But she didn’t and unfortunately she had a horrific and traumatic experience.

And that is just one story.  I hear stories of regret every single day.  Things like “I should never have married him, I should have known that he was abusive”,   “I don’t know why I hit him, I wish that I hadn’t”,  “I was so stupid to have believed her” and one of the most common ones “I should have insisted on him using a condom”
Unfortunately it is too late!
Yes, it is too late to change what you did.
But the thing is that if you did something ‘stupid’ or even something not so stupid that still had negative consequences, unless you know how to tell the future (and I sincerely doubt that you can), you had no idea what would happen as a result.
In simple terms:
You most likely did the best that you could at the time.
It is easy to look back with hindsight and berate yourself.  As far as I know, nobody ever ‘fixed’ the past by beating themselves up about it.
It is what it is, it was what it was.
Bad things happen to good people.

You can go a long way by forgiving yourself for doing things that you did not know or understand at the time.
You are human, you are wonderful and therefore you make mistakes.
Try your best to let it go.  Try to be more gentle on yourself.

There is this lovely quote:
“Everyone makes mistakes in their lives, that is why pencils have erasers”
You are allowed to ‘erase’ the past and move on.
Even better, you are allowed to redraw your life story, building on what you learned from your mistakes – and this version may be even more awesome than the one that you set out to write in the first place.