I too was bullied by a group of thug bogan boys at school. When I turned around one day in class, and said 'Shut UP!' the teacher finally decided to take notice, and issued me a detention. (So I hear ya.)
About a year or so later I fell into a group of girls who only befriended me to torture, use and humiliate me behind my back. It's been many years in the making that I can even have female close friends.
Uh, trust. It won't come back overnight, but it will happen.