скорее всего не 120-150 букв, а слов
Hello my friend!
How are you!? thanks for your letter! Sorry I haven't written for a long time. I was busy.
I want to give you some advice. You know it is a usual thing which happens with new pupils. First never give up. I am sure everything will be fine. You mustn't pay attention to these bad pupils. You need to find a friend in your class or in your school. You know I am always with you. You are good, kind and fine person. They will see it soon and will stop bulling. You must tell everything to your parents and teachers if you don’t like this school. I am sure they will support you.
Sorry I have to go.
Write me soon!