CHICAGO – A Chicago real estate management company is suing a former tenant for defamation for complaining on Twitter about mold in her apartment. Horizon Group Management filed the lawsuit against Amanda Bonnen, the former tenant, on Monday in Cook County Circuit Court and is seeking at least 50,000 dollars in damages. Horizon, in its suit, said that on May 12, Bonnen wrote a “false and defamatory” message on the micro-blogging service. “Who said sleeping in a moldy apartment was bad for you? Horizon realty thinks it’s okay,” said the “tweet” sent from Bonnen’s since-discontinued account at @abonnen. Horizon said the statement was “wholly false” and had “greatly injured” its reputation as a landlord in Chicago.