The family of a south suburban woman who was fatally struck by a CTA bus last week on a crowded sidewalk at Michigan Avenue and Lake Street has filed a lawsuit against the transit agency. Aimee Coath, 51, was hit by the No. 148 Clarendon/Michigan Express bus just before 6 p.m. June 2, according to police, the CTA and the Cook County medical examiner’s office. Coath’s daughter and son filed a two-count wrongful death suit on Monday against the CTA and the bus driver, whom the agency identified as 48-year-old Donald Barnes.