Tracy Morgan -- Breaks Down Describing Fatal Crash (VIDEO)

Tracy Morgan could not contain his emotions as he described the pain of the car accident that took his friend's life.

Morgan told Matt Lauer on "Today" ... it wasn't until he came out of a coma two weeks after the accident that he learned his friend, comedian James McNair, was killed in the crash.

Morgan broke down several times as he described the torment of the crash ... both physical and emotional.

Morgan said he has good days and bad ones ... and forgets things from time to time. He suffered a serious brain injury from the crash. Tracy says he deals with nosebleeds and headaches, which he tries to hide from his family.