"Forty years ago, I did something terribly wrong that I deeply regret," Collins, 67, wrote in his statement to People. "I have been working to atone for it ever since."
In this clip from his interview with Couric, Collins explains that one of the most important factors in his road to atonement has been his faith.
"In the church - and this is actually one of the things I love about the church, it's really one of the main things about the Christian faith – Christ says, in so many ways, 'Bring me that about you which is broken,'" Collins told Couric. "And most people are broken in some way."
However, Collins admits that he never wanted this side of him to be revealed.
"Most people either get to, or have to, or choice to hide it. This came out. I didn't choose this to come out. I didn't want to have to deal with these things publicly," Collins said. "I had dealt with them very, very strongly and committedly in my private life."
Couric's complete interview with Collins
will be posted on Yahoo, and will air on ABC's 20/20
Friday, Dec. 19.