Cutting off communication to a bestfriend

My best friend is always confused because every time I have some major problems I always cut off my communication with her. My reason is I don't want to appear having self pity or having her involved. She already has a problem of her own. And also I am afraid if I open up to her and just receive cold shoulders might tarnish our friendship. But still she keeps on calling or texting me, asking what is happening to me but still I don't answer her. Am I being inconsiderate or just the bad side of me.