I wouldn't tell her outright "your parents are dead" because that would be a blatant lie. Sure it's a very high possibility(and they ended up being dead anyway) but if you don't know for sure you can never give up hope. Either way, she probably would have refused to believe it until she saw them herself unless you constantly hammered it in.
I probably would have told her about the message too, if given the chance. I think the closest you can get to it is a line beginning with "I think i heard them die..." but I've never heard it, and aren't sure what you need to do to get it.
Originally Posted by Robbingrobin
No, she had not. Walkie Talkies don't reach from Macon to Savannah.
False. The stranger's car is shown in Atlanta in the beginning of the game, thus he could have been in Macon when talking to her(likely since he drives his car to Savannah in the end).