Aaron Hernandez wallowed in a “horrendous existence” brought on by head trauma before he killed himself in prison, attorneys for his estate said in their refiled lawsuit against the National Football League. The stark phrase was used repeatedly in the 86-page civil complaint filed Monday in Norfolk Superior Court in Dedham against the NFL and the Riddell company, the league’s official helmet provider from 1989 to 2013. The estate claims Hernandez, a New England Patriots tight end from 2010 to 2013, suffered chronic traumatic encephalopathy, a brain disease commonly known as CTE, after sustaining blows to the head while wearing Riddell helmets during a period that spanned from youth football to his professional career, which ended when he was arrested in 2013 for murder. “Aaron experienced a chaotic and horrendous existence in many respects, due to his [previously] undiagnosed brain injury,” the complaint said, adding that CTE symptoms include “aggression, explosive behavior, loss of concentration, mood swings, depression, apathy, and cognitive impairment.”