I agree with others on this! Your journey has just begun, so don't give up. When I was 18, I decided to go to college. My group of friends were unsupportive and offended that I was "leaving them" (i.e. their way of life) to go to school. Consequently, none of them ever talked to me again. At first it was very hard. I had this tiny one bedroom apartment and aside from going to work and to the gym everyday I didn't do anything except write in my journal and spend time alone. I worried that I might be alone forever, and probably felt a lot like you feel now. The moral of this story is that the changes I made were the right ones, and your personal development stuff is correct- you're opening up space in your life to bring better things to you (not drug-addicted friends). Be patient and have faith that you're on the right path.
I think balance is important as far as keeping you motivated, and if feeling isolated makes it hard for you to press on, then I would also recommend that you get yourself out there. My vegan friend joined several vegan pot luck groups, and also a running group to meet people. Even going to a gym everyday can help you to feel less isolated. Action is key, so start working on attracting new people to your life; the kind you want; the kind that inspire you!
