salut!! voici une idée de ce que tu pourrais écrire:
hello mate,
i know you are going through a rough time and people aren't really nice to you but i want you to know that i'm here if you need someone to talk to, i have also been bullied in my past. People used to make fun of my body and my low self confidence, i went through this thanks to a friend and by telling my parents and teachers about it, also by telling myself everyday that i was worth it and people were just jealous. I don't know if that will help you out but know that you can't give up you have to keep fighting, don't hurt yourself or worst because that's exactly what they want you to do and you don't deserve this. You really should talk to people about your problems and they will help you, i am here for you.
voila j'espère t'avoir aidé!!