He says what goes around comes around.
It is so hard for the ones to love us the most to help us how we need to be helped. the same with understanding. Sometimes we want to help someone get thru it and we just don't know how to do this. Therefore I think that JT and FHN have really seemed to have helped you get insight into a way possibly to get the yuck out and get past the anger you are feeling.
I tend to stew on things too long and for many years when wronged I could not let stuff go. Things would just get under my skin and I would really throw my whole life off course because I would have these thoughts go thru my head. all of them were justifiable reasons for me to be upset and probably see a therapist for a long time over.
Then one day I had someone tell me while I was on a rant about injustices in the world...especially my world, (actually they asked me a question). the asked me if, "I had to go home and sleep with this person?"
Of course not because this was a work situation...(this instance) and somehow those few words asked to me made me understand. That it is just that. A job I went to and it is a means by which I keep the real things in life that are important to me happening. It is a paycheck. Some other poor person had to actually live and bear the pain of loving such an @sshole and well the truth of the matter was...It wasn't me. Thank God for that.
So really..this dentist, he can stay and let his practice suffer from his mistakes and in short what your husband has said is true...It all comes back around. I am not sure if I believe it is Kharma, or "reaping what you sow"...but if you do negative things, if you do not treat people with respect, and you just bumble your way through life with no regards to others, well IMO you are not giving your best. When you don't give your best to what you do...anything you do...you get a substandard product. (For example: he does not have a great employee like you) or also he is missing out the fact that he cant even see what a valuable player you were.
I used to say to my ex-husband when I was mad...towards the end...that he had no class whatsoever. He had a treasure, a real treasure in his kids, stepkids, and wife: the whole situation I likened us to a vintage wine or a fine sportscar. You know something some people would spend a lifetime to obtain and would cherish it for forever. Shine it, or open that bottle on such a special occation, and then savor the taste and feel the moment of enjoying such a delightful treasure. I would say that he was like a person that had such a treasure and could not see the value. He drove us like we were last years Yugo and with total neglect, never checked the oil, no care at all for us and swigged us down like we were a bottle of Night Train picked up from the local 7-11.
I am thinking that dentist really did not see the treasure in you....and your looking back is throwing your pearls to the swine. From the sounds of it he deserves none of your time. And letting his sorry butt get under your skin is still letting him have your treasure (your mind).
I know it is easier said than done..but just remember, That you don't have to go home and sleep with him.