In the second segment of his televised interview with US talk show host Oprah Winfrey aired on Friday, Armstrong clinically sifted through the rubble of a career destroyed by the exposure of his use of performance-enhancing drugs.
A day earlier he had admitted to what the sporting world had long suspected, that he had cheated his way to the pinnacle of professional cycling by blood doping and using banned drugs such as erythropoietin and human growth hormone.
The 41-year-old equated the lifetime ban handed down by the United States Anti-Doping Agency (USADA) to the "death penalty".
Armstrong remained stoic as he recounted how his sponsors fled, and along with them tens of millions of dollars in income disappeared in a single day.
"I don't like thinking about it, but that was a $75 million day. Gone, gone and probably never coming back," he said.
Armstrong appeared saddened when he recalled the day he had to stand aside from Livestrong, the cancer foundation he set up, but it was when questions turned to his family that Winfrey finally struck a nerve.
The Texan fought back tears and paused to gather his crumbling composure as he talked about admitting to his 13-year-old son Luke that the stories about his father were true.
"When this all really started, I saw my son defending me, and saying, 'That's not true,'" said Armstrong.
"That's when I knew I had to tell him. And he'd never asked me. He'd never said, 'Dad is this true?' He'd trusted me.
"I told Luke, I said, 'Don't defend me anymore, don't.'
"I said, 'If anyone says anything to you do not defend me, just say, 'hey my dad said he was sorry.'"
Painted as a relentless, ruthless athletic machine, the moment of raw emotion was one millions of viewers had tuned in to see, offering a rare glimpse of Armstrong's human side.
Having described himself as a man who is always in control, Armstrong struggled to contain his emotions again when Winfrey asked about the impact the doping scandal had had on his mother.
"She's a wreck," he said. "(But) she's a tough lady and gotten through every other tough moment in her life.
"It took seeing her to really understand that this has taken a toll on her life.
"I'm deeply sorry for what I did, I can say that thousands of times and that may never be enough to come back."