Jade,
I also found that talking to the Head of house was of no use whatsoever.
She said that she is always hearing kids saying that they are going to "batter" someone and that it doesn't usually mean anything :( What a loaf of c**p!!
I found that going direct to the Headmaster was the only way forward and boy did things move then! He didn't seem to like the fact that I was critical of the Head of House. Tough, it was my daughter involved and I would have moved mountains to get things put right for her.
You really should try to tell someone about this. Your school life should be happy and free from fear. No child should ever have to go through school contemplating suicide. Please talk to someone as soon as you can.
Thinking of you
Love Kate xx