My son wants to die

I am broken and I don't know what to do. My son is 15 and is going through chemotherapy and today he told me to just let him die and he doesn't want to donit anymore. No parent ever wants to hear that. No parent should have to bury their child! And my mom is pissing me tf off because she's not getting any attention and nobody comes to see her yet she doesn't check up on her grandson going battling cancer! I have bigger things to worry about than her bitching. My son says he hates the way he feels, he hates the way he looks, and he just wants it to be over... How as a parent do you respond to that?! I cried when he told me this and he started crying saying he didn't want to make me sad, he's just tired and wants it to end. My heart it broken... I pray no parent goes through this...