Why did you allow them to take you to the "back room?"
Isn't the correct play to simply head for the exit?
So far as not "lawyering up:" did you call Bob and talk to him about your options, and the likely recovery amount?
C'mon man, you say they roughed you up and broke your arm: in this day and age that seems egregious.
Talk to Bob; could be it can be settled quickly without a lot of publicity.
Anyway, the damage is done as if you showed ID they have your name, address and pic as does OSN.