my best friend is dying and all i can do is watch :(

how can i feel positive :(  how can i feel hopeful when  i am sitting there watching dusti struggle to breathe..struggle to drink water..refuse to eat..how am i supposed to keep forcing little bits of food down her throat..or forcing medicine down her throat and all she does is lay there and cry and try to force air into her body..i dont know what to do and each day she gets smaller and smaller..she has no energy to fit me anymore..all she does it lay there..and i dont know how to help her..i want to take her to the vet and demand that they fix her..that they tell me whats wrong with her..but even knowing may not help right now..