Wow, that story brought a tear to my eye. Another reason for parents to teach their kids not to bully. The things you did after being teased like that would be what a lot of people in your shoes would have done. I wouldn't beat yourself up over it.
Just curious, did your parents ever encourage you to fight back when you were little? Have you seen any of the people who were mean to you since you moved back to Iceland?
The worst is behind you, and it sounds like you are more in command now than ever!