Friends leaving and confusing times?

Elementary was a nightmare. I had 2 real friends that actually liked me. To bad i was to busy trying to be with the popular girls. By 5th grade they where in a different cl and my "friends" had turned away on me. I was pretty much a loser who wondered from table to table, yet I didn't want to leave elementary and move on to middle school. 6th grade comes around and I meet 3 girls will call them, Cindy, Beth, Suzy, and heather. Anyways, 6th grade was picture perfect and I loved every minute of it. 7th grade rolls around, and heather and Beth aren't the greatest friends anymore. There drifting away, and heather and Suzy are becoming greater friends. Beth soon just drifts off in the the background of my friend circle. Cindy had always been my partner in crime and we love each other dearly. Then Suzy and heather meet these other girls, A and B. They smoke pot and drink. Cindy Beth and I don't want anything to do with that, so they let go and but I'm having a hard time leaving them. I got so close to Suzy and heather that it pains me that there doing this at such a young age. And I want the way it used to be in 6th and early 7th grade. But its not happening, im getting put down by them since I changed lunch tables away from them. so I guess my question is how should I let go and deal with the fact that I just lost 2 good friends? I also still want to be okay friends with Suzy I mean she has the exact same cles as me in 8th grade and I rather this not be awkward for us. Thanks for reading this very long post...sorry about that.