system
A chat on subreddit /r/NoStupidQuestions
human
There's 3 criteria we can ask ourselves in these situations. 1. Does anything need to be said at all? 2. Does it need to be said right now? 3. Does it need to be said by me? It looks like he's going to find out. Saying it right now will not change anything. And it isn't your place to tell him, it's hers.

Edit: wow. I didn't expect this to blow up. Thanks for the awards everyone.
gpt
Also, grief begets irational conclusions. He may resent you for telling him, even if he rationally knows you have nothign to do with it. Wait for the call, I'm not even sure if it is a good idea to let him you know before he did. I'd tell him she called after to give you a heads up he might need a friend.