So sorry to hear about your crash Robbie. I hope the damage is not too bad so it can be repaired.
The tyre might still have been legal but if there was still a shiny patch around the sides where it had not been worn in and you don`t lean the bike far enough over to reach them that might have caused the tyre to let go as well. I saw a vid on YouTube where a guy always cleans off the sides with soap and water even when they are new for this reason. Take a look at this -