Hi Fatty00,
First thing you should do is talk to your parents, I have a daughter who is 15 years old and I hope that if ever she has a similar or any kind of problem she will come to me and talk about it.
It will be very hard to do it by yourself and your parent will be there to guide you.
If your are not comfortable to talk to them, talk to a teacher or friends parent someone.
The most important thing is to control the thoughts. I can't tell you whether theyll go away or not because everyone is different but you just have to be strong enough to not give in.