Non small cell lung cancer stage 4 father passed away

With a heavy heart I write my beloved father passed away on the 8th April after being diagnosed with non small cell lung cancer. Being so fit and well still working enjoying life, after the only symptom being a cough my father was quickly diagnosed with non small cell lung cancer stage 4. That day was the day that broke my heart walking into that appointment coming away so devastated. It was much more aggressive than initially expected. And he survived a short 8 weeks. 4 weeks of those was waiting for biopsy results and his deterioration became so rapid. He had a very short window of when he was well so chemo was started with the hope that they could shrink the cancer. He had his first cycle and side effects weren’t too bad at first and day 8 he took the tablet part of the chemo and on day 10 my father’s oxygen levels dropped. He was admitted into ICU fighting infection. He had caught sepsis and everything they were giving was not working. He died only five days later. His mind was intact. The cancer had completely collapsed his lungs and blocked his airway and the infection made it worse. An earlier prognosis we were told around 12 months but where’s 8 weeks and where is 12 months. I sit and think about every single moment from diagnosis until his passing. I pushed for the chemo and they gave us a quicker spot. I pushed all the appointments but reality is that I pushed him closed to his death. It’s hard to understand why he deteriorated so quick. On diagnosis he was fit and well and after the biopsy things just changed overnight. I didn’t even know he was dying he was just tired still talking but weak and no energy and he fell asleep took 3 short breaths and left. I was so confused not at any point did it register that my father was at end of life. He was in active treatment right up until the end. My world feels like it’s come crashing down. I feel like he didn’t have a fair fight. I kept telling myself it was the start of a long journey , little did I know the journey was already going to end at the first hurdle. There’s so many questions I have and it doesn’t make the grief any easier. He was my whole world. I always thought I’d be able to see my parents grow old where I’d have a real opportunity to care for them but in a short 8 weeks that’s all I had. Everything going forward will be hard. I don’t know what the right or wrong way is to grieve. Right now I don’t want to be around people or involve myself in conversations. I go to the graveyard every day to sit with him and even that doesn’t bring me peace but some days I find myself going there more than once in the day so maybe it does give me some peace there I don’t know. It’s a horrible illness and I’m scared of the word cancer because I just assume death. I don’t know if it will get easier in time or manage to live with it but i know I’m struggling to accept how quick things have happened.