Quote Quoting chefM
Do I have any legal standing to pursue in relation to the statements made in the letter of dismissal? I am also wondering, have there have been any slanderous statements made about me to potential employers?
You can only sue over slanderous statements that you can prove were made. If the statements were made only to you they are not actionable - to be actionable, the false statements must be made to one or more third parties.

Quote Quoting chefM
There was a statement made in the letter:
“…before you become too defensive, may I respectfully point out that several other restaurants in this area have had to make the same regretful decision as I in the recent past.”
This raises another question: can I pursue a claim of slander against these previous employers?
If you can figure out what they said and prove that it was false, you may be able to establish a claim (depending upon what was said).