I told my BEST friend about how serious my dad's health is (large tumour in kidney, possibly cancerous) and after inquiring about how he got there and details on his medical condition...all she said was ok? OK!!!!

Gosh, I can't control my anger...we're not acquiantences, you're my BEST friend and you couldn't even say "I'm sorry about your dad" or "I hope he feels better"? You say "ok" if someone asks you how you feel, not when someone is falling apart.
I don't know why I bother with friends at all.