Yep, this is where Brett started to become a man. It had to be Brett who revealed what happened to Dustin. Billy thinks he is the hero of the story, but he's not. If Billy were the hero he thinks he is, he would have not listened to Mike and told someone what was happening to Dustin. He's constantly being manipulated by the adults in the story and being forced to carry their secrets for them. He's smart, but he's not wise at this point. He believes people he shouldn't, and gets taken advantage of constantly. And, of course, he's a coward. Half the story is Billy trying to conquer his fears.