Couple of things:

1. The bank likely ended up with the house after foreclosure. If so there is no reason they can't rescind the foreclosure sale and let you close the short sale. They can even put the recission in escrow with instructions that it can only be recorded at close of escrow on your transaction. If it has already been a while, and your buyer has walked it may be too late for this approach.
2. If you got the short sale approval in writing, or some acknowledgement that the foreclosure sale was a mistake, you could talk to the attorney about  putting a lis pendens on the house and suing the bank. I doubt you would win, but you might be able to negotiate a more favorable credit reporting or something in exchange for dropping the case and removing the lis pendens.
   
3. The bank does have to evict AND you will get a note on your door to vacate as part of that process. They will likely also offer you $1-$2k to move and lean the house clean. Take the money and move, no reason to add an eviction lawsuit to your woes.

And please remember - I'm not an attorney, so this is just my two cents.

I had a similar insident happen to my client.  I was so upset by the Nonchalant approach of the Short-Sale negotiator, and how quickly she brushed her error under the rug to avoid consequence from her superiors.

I would have think, that there some stronger recourse since an "approved short-sale" in a sense is an agreement/ contract between bank and borrower.