I wasn't someone who would physically attack people, but I would relentlessly verbally abuse them. I'm not sure about the legal consequences these days but I know that if the person I picked on punched me in the face, I'd probably back down. This is what I have told my kids if they ever find themselves bullied. I'm not sure about the circumstances of the OP but I do think if you allow the bullying to fester, then kids who normally wouldn't bully start looking at you as a target and join in. The key is to not make yourself a target and if they know every time they bully you, that you will fight back tooth and nail, eventually they will choose someone else. It's sad and unfair, but true. It's like Lord of the Flies.
The one thing that makes me glad that I'm not younger is the fact that I didn't have the internet when I was a kid. I know for a fact I would have engaged in cyberbullying so I'm glad I never had access to a tool like this when I was at my worst.