I had exactly the same experience. I was in a public school full of assholes and teachers that couldn't care less about any bullying taking place. Those few years were probably the worse years of my life.
I grew significantly and became a different person when I was moved to a different school.
I still think it taught me a lot about the world and how people really are. I really lost a lot of faith in humanity in those few years and still see the world as cynical in which all people are in it for themselves.
Did it make me stronger? Maybe. But also I wish I could see the world more positively as a lot of people that have been shielded from those experiences seem to do.