My understanding of your situation is that you stayed on with the abusive boss after he sold the practice to a new owner. It sounds like he was staying on for awhile to let the new owner get up to speed and he needed your help. So, you need to show why you quit just then when you had endured the abuse for 10 years. You will be denied unemployment if you quit without good cause, so you need to show why you could not work for there anymore.
First, go to the hearing and appear in person if you can. I know many people do these by telephone, but think about it this way, essentially you have a "he-said, she-said" situation. The best way for the hearing officer to ascertain credibility (who is telling the truth) is to be able to look everyone in the eye. Also sometimes the employer doesn't appear in person, and that will benefit you---this is obviously important to you and you are hear to tell the truth.
Second, (and this is the tough part) do your best to stick to facts and avoid emotion, feelings or name calling, etc... Ultimately you are entitled to unemployment if you were terminated and there was no a a just cause for the termination (ie.. you were stealing from the business....) If the hearing officer views you as a professional individual, focused on the facts that will help in establishing your credibility. If you are over emotional, accuse everyone of lying, etc... that may tarnish your credibility. Keep to the facts and stay professional.
Finally, don't overstate your case and avoid irrelevant information that might place you in a bad light. For example, you begin your question describing that you worked for a verbally abusive physician who sold the practice on 6/1/11--based on the facts that you have provided, this appears to be irrelevant and unnecessary to make a decision on your unemployment. Moreover, a hearing officer, who is trying to determine whether you are eligible for unemployment, who hears your description of your old employer, might simply conclude that you just don't get along with anyone who employs you (fairly or unfairly.)
You quit because of a medical condition caused by your employment, which made it physically and mentally impossible for you to perform your job. You need to bring proof of your medical condition. If I were you, I'd speak with a workers compensation attorney.