I don’t know how to stop it… but talking about it can only help.
I was always a big kid, but that didn’t keep me from getting bullied at school, usually picked on because of my weight or that I was a Mormon (and usually the only one in my grade). Thankfully, it stopped by high school (probably because I was, again, big). I’m glad to see that there’s a documentary out there like The Bully Project. Bullying is horrible, and too often it’s ignored by schools and misunderstood by parents.