Glad you're okay. How old is the LW barrel? I ask because the XDm has pretty good case support and later LW barrels don't have the support they used to have. I don't know what powder he used, but if it was Longshot, from what I've tested it's pretty good up to about 10% over book in the .40 with a well supported barrel. It sounds like it could have been a lot worse, any pictures of the gun and the brass?
"Condemnation without investigation is the height of ignorance."