maybe it is best that he has worked it out for himself - means he has understood enough from observing what is going on to project where it ends up.
Although it is awful - it is also positive that he has that understanding.
Maybe a way forward now is to talk about how difficult things are for Steve - so that in the end Elliot sees dad dying as a positive thing - in that it is easier for him than what he is going through now.
Do you have a feeling for how close the girls are to what Elliot now understands ?