Going to reserve judgement because I didnt see what happened. I will say this though. If i have groups of puppies in board and train and one gets over aggressive with another and starts to ruin the experience of the other i will step in with a physical correction strong enough to stop the behavior, and if necessary repeat it with gradually stronger corrections until the puppy cools it. It doesn't ruin them. If done right and consistently it teaches them how to interact in a proper way instead of the usual lord of the flies puppy free for all you see at a lot of places.
Did she go overboard? Maybe. Should you have seen your puppy was doing things that bothered another person and stepped in to stop it instead of insisting your judgement was the right one? Probably. Dunno how much sympathy i have for you.