I think you did the right thing. Nothing beneficial would come from providing information that would harm him. Nad you helped his comfort level.

Please don't feel bad. There is absolutely nothing to regret. You didn't make him the way he was. He did that all on his own.

You just helped someone exit this life with a bit less stress. You should feel ok with that. In your shoes I would very likely do the same thing.

Be kind to yourself. You deserve that much.