Struggling to cope with this :(

All i can think of is my Grand-Dad. How much can one human being take?
He lives in a care home now, and will do for the rest of his days.
He doesn’t remember who I am, who my Mum is, or even himself.

He suffers from the following:
Alzheimer’s Disease
Dementia
Parkinson’s Disease,
and to top it off, he’s been recently diagnosed with Skin Cancer.

My mum came into my bedroom last night crying her eyes out, he’s got to have an operation and Radiotherapy ASAP. So he’ll be in for Christmas.

My Great-Nan, who’s been unwell recently and has not long been released from hospital, (which she shouldn’t have been) - was found collapsed in her flat on the same day as finding out about my Grand-Dad’s operation. She’s not to be released until after Christmas. 

I’m not silly, I know that both of them aren’t long for this world, but for my Grand-Dad, he has already gone. He’s just a shell of himself, he doesn’t remember his family, himself, how to eat, read and the rest. It’s hard to grieve when he’s not actually gone, he’s still there, i can still go up to London and visit him. (which was the single most hardest and most emotional thing i’ve ever done in my life so far)
It’s unsettling, and it’s a cruel, cruel world. I wish he could come back, and be him again. I hate the fact he has to live his last years as a practically mindless soul.

I’m so broken hearted about this, and yet I struggle to cry, or get angry. I just go quiet, I want to be able to grieve because I can’t sleep, or concentrate on anything. I breaks my heart to see my Mum crying every night. 

I just want my Grand-dad back :(