My DD6 has some issues with perfectionism but it has gotten much better. When she gets her homework back and something is circled wrong she erases it and fixes it.

It's like her wiping up her spilled milk, she fixes it, forgives herself, and feels better. My reaction to this helps too. My DH
had to really work on this.

This is very simplistic. Please don't think I'm belittling your situation. But this has truly helped our family. I think kids pour their own milk in important just for this reason.