Sylvia, I don't really see that there is anything for your previous employer to gain by not providing you everything in the workfile. He is bound by the same record keeping requirements as you are. Pull out your USPAP book and you will feel better. Read AO31 and quite a few Q&A about retention and access. I wouldn't sweat that really.
Early in my career, I worked for 2 large Appraisal firms. The first one just under a year and the 2nd somewhere around 7 years. Neither were happy when I left. Generally speaking, I think that's just the nature of the business.
In retrospect, I get it. A company spends time and money to train you with the expectation that you will "repay" them by staying as a valuable employee. If you leave in the first couple years, they lose money. In your case, you stayed 10 years so in my mind you paid your dues. Doesn't automatically mean you will get a pleasant send off though
As far as "stealing" an AMC or Lender client....Some AMC and/or Lenders approve the Appraisal Firm and some approve the individual Appraiser. That is the first thing I would find out if you don't know. If you were already approved individually and you gave notice, I would consider that above board. But, if it was the firm that was approved and you applied for individual approval WHILE you were still an employee, that might be a little sticky. If you waited until you left to apply for individual approval, as long as you did not sign a non-compete, I can't see that you did anything wrong.
Unfortunately, I am not a lawyer and my opinion means zip
Good Luck!