You did'nt fail as a martial artist, but remember that in a dojo you are just training, my sensei always tells me that you can't get mad inside de dojo with the people you train because they are your friends, you are there to train and become better, so that in the street you can protect yourself. You are not there to get mad at some cocky guy, and your sensei should have told him to quit doing what he was doing instead of beating him, he will never learn that way. You need to have respect with the people you train, we always thank everyone when we finish because they make us better persons.