Struggling with the loss of my Dad

Hi, Im new to this and Im not even sure what I will get from this. Maybe I just need to vent. I lost my Dad 3 months ago to a brain tumour. He was only 66, fit and healthy, no health problems at all. Then start of March he has what we thought was a stroke... It turned out to be a brain tumour. The next 9 weeks were, well hell. He was in and out of hospital, we found out it was a glioblastoma and nothing could be done. He then fell ill with pneumonia so any treatment to prolong his time with us was cut short. He then suffered another seizure which he didnt really come back from, we got some words from him. We were then told it was time for hospice and he may have 2 weeks to live. 

How from 7 weeks ago he was fixing my car, popping over for a cuppa to see his granddaughter, helping his grandson fix his bike... Has it come to this.

I cant help but see him how he was those last 2 weeks, that wasnt my dad, it shouldn't have been him.

Everyone says in time things will be better, he is out of pain. But nothing makes me feel better. I wake every morning thinking it's not real... Then realise it is.

How can an illness be so so cruel