You'd think, they would have recognized his voice...probably. Could me someone else, but suspiciously sounds like the addict.
Let it go, mom. It might make YOU feel better - most likely not - but it won't solve anything or make him any more shameful than he already feels. Be the bigger person and forget the War of Words. If he didn't immediately raise concern and the need to help in Gram and Gramps he will get the clue that they aren't a soft touch, either.
So sorry this is reaching out to other family members. That's always been our biggest concern, but thankfully - other than her siblings - our daughter has kept her extended family out of the loop.