Awww...I am sorry that you are having to go through this. It is hard to watch our kids learn these lessons of life.
One way I think made it easier for boys to deal with the deaths of both Grandfathers and one Grandmother was that we told them everything and the youngest was 9 when my Dad died, but we didn't hide anything from him either. But I know that your situation is totally different than mine so I'm not sure if that would help Ethan or not. When the boys would talk about their grandparents right after their deaths, I would remind them of something fun that they did with them because I want all their memories of them to be good and even when they think of them now, I don't want them to be sad because they are gone, but to be happy because of all the good times that they had with them when they were here and to know how much they were loved.
I'm sure it will just take time, but maybe you can encourage Ethan to talk about your Grandfather so that he will know that it is OK to talk about him and to cry because he will miss him.
Hugs to both of you
