Re: verbal abuse from a teacher
My first aikido teacher was like your own, although not with me I might add. The students he was like this to, he said he was doing it for their benefit. I remain sceptical.
Technical profficiency in aikido is just that, nothing more. You can be brilliant at it and still be a bad character (see the BK thread). Only if you embody and live the principles of the art, do you transform yourself into something greater.
As has already been said, just about anything can be character building, particularly adversity. Knowing when something is not right and acting with integrity, is not always easy, especially when you have a great deal of time and emotion invested in it. So your decision to stay or leave is part of the character building you want. As you do not want to be like your sensei, I suggest you seek out someone who displays the attributes you want for yourself.
I would rather be an average aikidoka of good character, than a great aikidoka who is not respected as a man.