Alleged Ponzi schemer and disbarred attorney Scott Rothstein filed frivolous lawsuits and authorized the creation of a defamatory Web site to attack opponents in a shareholder dispute for control of a Costa Rican hotel, according to a lawsuit filed by former clients.

Education services company Whitney Information Network and a subsidiary claim they ended up paying a $3.8 million settlement to mitigate damages caused by Rothstein’s alleged legal malpractice.