Grandma has passed and I'm not sure how to handle it

My relationship with my mother (and her relationship with literally everyone else in her life) was...complicated. But whatever anyone can say about her in any other capacity, she was a great grandmother to my son.

She got to be a major part of his life for the first 3 years and then for unrelated reasons we had to move across the country which was obviously very hard for her but I did my best to make sure she was still involved. She came to our new house once in the last two years but she and my son would Facetime constantly.

In fact, my son was the last person she talked to before she went dark 2 weeks ago. I finally got the police to enter her apartment today and received a call from the coroner. Personally, I'm obviously dealing with my own shit on this and have to fly out to where she lived and get some affairs taken care of.

The thing that is wrecking me the most, though, is breaking this news to my son. It's the first death he'll have to deal with outside of a cat he wasn't very close to (and was quite young). He has asked about death though. He knows what he's doing when he smashes an ant. He's asked me what graveyards are and we've talked about it. He's aware that people die when they get old but is confused why it can happen without being old.

My wife and I are trying to figure out how to deal with this....so I'm open to whatever the brotherhood of Daddit has to offer.