I think you should talk to an adult you trust and get some support. Ultimately you should report this to the police and social services too but get help in doing that from an adult mentor, someone you know you can trust (in real life, that is). As part of the process I'm sure you will be offered counselling to help you with the emotional aspects and the nightmares. I'm so sorry this happened to you. The good news is that you can regain control of your life again, with the right support.
Everybody else has already said it better than I could. So all I can do is offer my support as a member of your circle. Please feel better.