I wouldn't recomend telling the teachers that you are being bullied (like others have mentioned the vicious circle - and sometimes just makes things worse), I'd definately tell your parents though, or someone you are really close to who can try and help you through it. It's really hard speaking to your parents about things like what is happening but they are going to want to support you through it, is there no options of moving forms to get away from them?
Obviously if the bullying starts to get physical then you definately to be making your school teachers aware. Child Line will talk to you about it and hopefully give you some advice on how to deal with it - a lot better than we can here.
Like Immenseman said, there is also the option of just ignoring it, but if it continues day in day out, then eventually it will start building on top of you where you wont want to go to school anymore.
Fighting with them, or bullying someone weaker than you isn't the answer whatsoever.
This link may also help - http://www.connexions-direct.com/ind...eContentID=597
Regardless if he is or not, they have no right to be bullying him or even accusing him of being gay - merely on the basis he doesnt socialise with the lads in his class?