Has this friendship run its course?

I am a female and he is a male. This is a platonic e-mail friendship which has gone on since 2007 (we are ex-coworkers from 1998), but it's been on the rocks since late last year. We have grown apart, and I feel more self-esteem when I don't have contact with him. Basically, I am supportive of him, but he is not supportive of me, when it comes to our individual goals and aspirations in our lives. In short, it seems as if he doesn't care anymore. When I try to bring it up, he acts as if I'm the one at fault. Do I need to just cut ties completely or is that too extreme?