You are young still, so it might be hard for you to see this:
This continued for a long time, but a friend I met during second semester would always tell me she hated that I did it, and asked me to stop for her.
This is a friend. You need to spend time with her. She will lead you in the right direction and that's what friends do.
He would call and ask if he could come over so we could snort, and I would always say "No man, I quit." I went from seeing him everyday, to not even getting a call from him for about 4 weeks. Then one day when I came home, he was outside my door with a smile. We went inside, he broke 2 lines even though I kept telling him I didnt want one, and I ended up snorting it.
This person is not your friend. He might have been your friend, and he might be in the future, but he is not your friend now, and he will never be your friend as long as he is using.
Who you choose to call your friend at this point in your life is very important. Please think about what I said.