I would like to ditto what everyone has said so far but to add these few words and to also to say sorry to hear of your of loss

. When I first read this it was obvious you was in pain and reaching out and I think it might have taken an effort to share your feelings for a tragic loss, especially to those not known. :-/ :-/
I have not been in that situation but had an experience which was totally unexpected which I can only say, felt like suffering a blow over the head with a blunt object, you are disorientated can't take your surroundings in. I don't know how I would handle the loss of my mother as it is only us, and I have thought about this especially when attending others bereavement ceremony.
Been so close made things that much harder for you especially as you were considering him foremost even when you were ill. Forgive me if it appears like lecturing, I do not mean to do so.
As to sharing, it is written it is good for us to take each others burden.
Everyone has coping mechanisms i.e throwing themselves into work, hobbies etc. Someone said time eases wounds. I would like to think that loved ones may be there watching and encouraging us. In addition, I do not know if you are a person of faith but it may be worth praying about this situation. When I refer to praying it is more like having a conversation with your step father and it may possibly help to think of him.
One thing I'm really happy about is that he did not suffer in his last moments.
Just a final thought, it may sometimes be easier to speak to those not directly involved as you have virtual friends here.