I'm so sorry Nkf, I'm so so sorry...
Please don't feel guilt or remorse - you know he wouldn't want you to.
My mum died suddenly and I was full of the same feelings and the guilt was just crushing until eventually I had a dream/visit when she just held me and asked me did I not think that there were things that she felt guilty about too and that she now knew that guilt was a completely wasted emotion most of the time!
It's awful and horrible and agonizing, losing someone, in fact I want to type all sorts of rude words it's so bloody awful. I'm so sorry.
Please look after yourself, show yourself the love that you show to others. Also, the only thing I could grasp onto at the time was that Mum had taught me even more valuable lessons about what is really important in life, and wasn't she wonderful for giving me that important knowledge on top of everything else she'd done for me - you father, with his passing, will have passed on this understanding and knowledge to you too, just as he has passed on so much else and I think that he would be proud to know that he'd done that for you, his daughter.