I doubt 'iam disappointed in you' is said out of anger. Disappointment comes with sadness or is meant to break someone. It's proved that saying these words hurt many children more than a beating up, same counts for being ignored. Even little children treat another this way and they do it on purpose and to be mean, to shut you out.

I can't remember if I ever heard those words. I heard many fired at me 24/7 and I know at a certain point I closed my ears and waited till it became silent.

The being stupid, included by teachers I remember very well. I know their names, their faces and how they didn't hesitated to beat a child. Incapable people with no intention to find a way to explain in a different way what is meant.

Unlike you I never thought there was something wrong with me. Adopted, hated, discriminated? 200% but not that me being stupid caused their behaviour.