You can consult with an attorney who handles defamation matters, most take a $5K retainer up front to pursue these issues in my experience, so weight whether the cost outweighs the benefit - good luck.
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Consult with an attorney who is experienced in defamation and privacy law. I agree with the previous answer, the cost of retaining an attorney to press a claim against those who are publishing false information about you when measured against what you could recover is probably too high. In any event, you should address the situation in writing to your property management company denying the claims and pointing out that pool use is a part of your rent, and that it is wrong for the manager to bar you from the pool based on unsubstantiated complaints. Good luck.
Defamation lawyers are very expensive, and without sustaining a monetary loss, you would likely pay the lawyer thousands more than you would recover, but it's your dime...
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