My dad died

a few days ago my father died from lung cancer and I feel like ive lost my best friend. It hurts. I can't believe I'm never going to se him again and it all feels so unbearable. He was only diagnosed a few months ago and so his decline was very quick and having decided to be there when he died it has now traumatised me - I saw his last breathes and I can't stop thinking about how he looked, how he didn't look like dad. I don't know how I'll live without him.