New "Real Housewives of Miami" star Joanna Krupa insists she's not a high-priced prostitute willing to sleep with a stranger for $10,000, despite reports to the contrary, and now she's threatening to sue one website over the accusations, TMZ reports.

Krupa's attorney Marty Singer has fired off a letter to Nik Richie at TheDirty.com, claiming one of Richie's recent posts -- entitled "Joanna Krupa Is a Confirmed Hooker" -- is filled with defamatory lies.

The article in question quotes a man who claims to have had sex with Krupa for $10,000 through an escort agency, adding, "'The Real Housewives of Miami' should have done a better background check."

Now, Krupa is threatening to file a lawsuit against Richie if he doesn't pull the article, calling it "an extremely serious matter."

Richie is adamantly refusing to pull anything, TMZ reports.

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