Dwelling on could’ve, should’ve, would’ve is what’s keeping you from fully embracing what is in front of you now or what you should be looking forward to next.
What’s in the past is in the past and should remain there. You should not continuously punish yourself for something that a less matured you did. That’s not who you are anymore. And perhaps, it has never been who you were either.
Mistakes are supposed to make you wiser. They are learning tools. Stop using them as torturing devices. Let go of the past, enjoy the present, and look forward to what’s next.
Your real mistake is not what you did a while back, but what you are doing to yourself right now.