Sweetie, I was in your position two months ago when my boyfriend dumped me. I'm still finding it hard now and it's been 2 and a half months. What I did is cut off all contact with him, get rid of everything you have that reminds you of him, go out with friends, do what makes you happy, go shopping, listen break up songs(you may think they don't help but they do) write down a list of things that you hated about him, or what bad things he did(if he ever did) it works anyway, trust me. I've been there, done that :) It will be a long, painful process but you will get through it. You're only 13 and there's plenty of other fish in the sea for you :) So head up and don't let it get you down :) He was obviously not good enough for you anyway.
I know what that feels like and I tried to forget about him by taking my mind off of him. You can do that by doing things you like such as maybe listining to music, playing sports. Hanging out with friends. And trying not to talk about him.
Well, u might not get over him just right after u broke up. Depending on what ur relationship was like, u might not forget him 4 a long time. Don't panic! If u want 2 forget about him, do stuff that u love. Read a book, listen to music, watcha movie, doodle, go for a bike ride...I don't know. Something that u love.
Well,you just need to forget him!! and cut/rip everything he gave to you or reminds you of him and just get him off your mind...and if you even saw him again IGNORE him and never look at him even if you had to. and live your life normally and LIVE THE MOMENT hope that helped!