im sorry! well at this new school just try to talk as many people as possible and make sure u dont compromise urself just to fit in. hopefully, u can find a new best friend but still keep in touch with ur old bestie! im going back to school, but my best friend is leaving me, so i kinda know how u feel. best of luck!
Don't worry, just be kind to everyone and you'll have lots of friends. For your old friend, become penpals. I do that with lots of my friends... Or become phonepals. That works even better. If you need anymore advice, message me. :)