Why do old "friends" have such a problem accepting that you've chosen to move on with a "new" you?

I must admit that I'm more into self development these days. I enjoy learning new things, and quite frankly I do not have much in common anymore with ANY of my friends. I've grown a lot over the last few years and it was only when I pulled back from everyone that I was able to focus. A whole new world has opened up to me now. I'm more focused and my attitude is positive. I feel that I was being dragged down by these "friends" with all of their foolishness and issues. I'm more at peace now than I was when I had people around. This new me has caused a lot of problems with these friends, most notably one of them was so "offended" by the new me, that she basically began to slander me with lies, harsh words, and harrment, all because she can't deal with the person I am now. She even told me that the "old" me was more fun. Am I on the right path or is this just a phase?