How do you move on from past mistakes?

i often dream and overthink my past mistakes, some are even so stupid to the point i feel cringe. i know that its already done and nothing else i can do about it but i just cannot move on from it.

i even diagnosed with anxiety disorder, and i need medication just to sleep.

i am convinced that if i know to move on, my anxiety disorder should be cured by itself, but i still lost the fight. any suggestion how you guys deal with it?

When I was a child, I would lay awake at night, in retrospect it was anxiety and depression due to loneliness (only child, sheltered, private school with less than 10 kids).

What I did, without the knowledge or concept of anxiety and depression, was that I would let me thoughts run and I would use logic and reasoning to get through them.

“What if a kid makes fun of me for this and that?” “I would then do this”, and then I would play out every single possible situation in my head on what the most common, worst, and best outcomes were.

A decade of doing that helped me.