hello missb-
i too am realizing that most of my friends are addicts. and it becomes more and more painful to watch the fallout from their poor life choices. i think being a compassionate, caring person, i want to help them. but i now know that i can not.
it's hard but try to take care of yourself. if you have only one real friend, then so beit. you will not die of loneliness!
try to take steps to meet new people. perhaps take a course at the local college, or sign up for something you've never done before...like guitar classes, swimming lessons, or volunteer in the local community garden...
put yourself out there and break the cycle.