I just turned 30, and was diagnosed as having post-traumatic stress disorder.  I watched as my father died of a heart attack in our family car as my mom screamed helplessly, but what contributes to this diagnosis even more is my experience of bullying and cliques in school.

I was luckier than most in that I was always very assertive.  I would go head to head with bullies, so bullying didn't last long.  What did scar my psyche was the many times that I was pushed in and out of cliques/friend groups.  To have such intimacy with people, and then to lose it so suddenly and without cause is extremely confusing and hurtful - hurtful being an understatement.

It was difficult at the time, and the pain is less now, but I have had to slowly build trust in people again.  I still battle with trusting family, friends, and colleagues, because I have this apparently ingrained understanding that a relationship can change on a dime.  It is very unsettling.  Instability is a scary thing.

As far as bullying, kids are little shits sometimes.  Be assertive.  Stand up for those who are being bullied.  I can look back proud that I at least did that.  Though, there were instances where I bullied, and I regret those instances more than anything.  I hate knowing that I have caused anyone unnecessary pain, or made their life any harder than it had to be.

What kids don't understand is that life is hard enough - you don't need to add to it.  

Kids will tease or bully about anything.  I was certainly teased for my weight (that's a  time-old classic).  I was once even teased for having a dead father (the guy was a complete idiot, and I said "Really, you are teasing me because my father died" loud enough for everyone to hear, and that ended that).  I was teased for being a "goth," and the guy later ended up a friend.

Know that you don't have to fit in.  The majority of the people in this world are idiots - bleating sheep who need to glom together and follow a leader.  Don't be afraid to be yourself, stand up for what you believe in, and break away from the herd.  In the end, that will be what defines you and makes you who you are.  You won't regret standing up for the kid being bullied.  You will regret bullying.  

To anyone out there who is being bullied, please stick it out.  Life WILL get better.  You will eventually find your place.  I promise.