You need to speak with an attorney that handles defamation claims. Your question givens no information and a defamation lawyer will need the details of your case to determine if you have a claim, who any potential claim may be against, and the extent to which you may be able to recover.
Very likely the time limits for bringing a defamation case have long passed. Confirm by consultation with a local defamation or employment attorney.
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In most states, the time period for bringing a defamation action is one, butr no more than 2 years and usually commences to run from the date of the "publication" of the defamatory remark (whether verbally or in writing). You face a likelihood that you are barred from commencing a defamation action given the passage of 6 years, but consult an attorney in your area to see if the delay in the resolution of the criminal action acts to give you an extension of time.