Andrew Young, testifying in Greensboro, N.C., under a grant of immunity, described his own relationship with Edwards as one that became so fraught they almost got into a fistfight on at least one occasion.
Edwards, who represented North Carolina in the Senate for one term, is on trial in federal court. He allegedly raised money illegally during his 2008 campaign for the Democratic presidential nomination to pay off Rielle Hunter.
Young said he was told concealing Edwards' relationship with Hunter was still "the most important job on the campaign" after the former U.S. senator dropped out of the race because he had hopes of the vice presidential nomination. At the time, Young and his wife, Cheri, were living with Hunter and helping to funnel payments to her, he alleged.
In one conversation in the summer of 2008, Fred Baron, the campaign's finance chairman, told him to "take a deep breath," Young testified.
"Mr. Baron wanted us to try and hold on until the Democratic National Convention," Young said.
Notable deaths of 2014 [PHOTOS]