"It was not easy for me to answer direct questions about him, what we went through. There's a lot at stake. I've read in the papers that it could be up to US$120 million [damages].
"I don't know what he thinks but I know what I need to do. You answer questions that could affect that and that is mind-blowing but I went in there and told the truth. But it [also] sucked [as] there were some questions about his character, with him sitting right there, some of the bullying and stuff."
Hamilton said the US public had reacted positively to him since he told the truth. He suspected the public felt Armstrong had not told all the truth.
"I think the public wanted to hear the truth and they got the major truth - that he doped during his seven Tour victories - [but] they want more of the truth. He held back a little bit for various reasons.
"For him, for the sport of cycling, for all sport, I think we do need to hear the whole truth. Whether or not we'll hear that, we'll see."
Hamilton said he had respect for New Zealand cyclist Stephen Swart, who stood up to cycling's omerta to try to blow the whistle on systemic doping. Swart went public in 2005 describing how he, Armstrong and others decided to use blood-boosting drug EPO in order to compete in the 1995 Tour de France.
Cycling and sport in general must remember lessons from these scandals and disincentives to cheat must be high, Hamilton said.
"In terms of its future, I don't know, one day at a time. But we can't forget what happened. We have to keep the sport heading in the right direction and I think we are heading in the right direction. History does repeat so we need to be careful, we need to remember and to work hard.
"The experience of the Tour is crazy, incredible, the Super Bowl of cycling, for three weeks. We talk about the dark stuff, there were a lot of good experiences. It's a beautiful sport, incredibly difficult and I think that's what led to the doping in cycling."