I say don't go to her with your issues unless you want her to change the subject, start talking about herself, or want to feel like she doesn't care. It sounds like you've known her a long time. Has she always been this way? Perhaps keep her as a friend, but try to accept the reality of where she is in being able to be supportive. You can also ask her what's up and why she does that, if you think it might be helpful.