There is a lot of good advice on this thread. I particularly agreed with what Mr. Riggs and Mr. Ledyard had to offer. As Bruce Lee once said, "absorb what is useful and discard the rest." Recently, I decided that a particular individual had to leave our dojo because he had injured another on the mat (there had been other problems with this individual, too). I would have not known about the injury or some of the other problems had others not informed me, and as Mr. Riggs so eloquently stated, injuring someone (outside of accident) is intolerable for a number of very good reasons. Now, at my dojo, there seems to be a renewed positive spirit in training among our members, and those who stayed away are returning. I have found over the years that abusive people who come to train eventually have been weeded out, but usually not before the problem has come to the attention of the dojo-cho. I hope that what happened to you won't keep you from continuing in your training.