I really miss my old best friend? (please read)?

I say you should keep in touch. You can write letters to each other. It may sound silly since it's a technical world today, but I'm 17 and still send letters to my friends even though we have the internet and cell phones. It shouldn't cost you anything to just send a letter. As for now, you should discuss with him about how you should deal with your feelings. Since you guys are 12, you have many years ahead of you. That is really young, and your feelings may change later. The best thing to do is to stay in contact as see where you are later on. If you meet someone else, the best thing you can be is his best friend. :)