Stephen Collins has broken his silence. In a lengthy statement to PEOPLE, the former '7th Heaven' actor publicly confesses to sexually abusing underage girls decades ago.

"Forty years ago, I did something terribly wrong that I deeply regret. I have been working to atone for it ever since," he said. "I've decided to address these issues publicly because two months ago, various news organizations published a recording made by my then-wife, Faye Grant, during a confidential marriage therapy session in January 2012. This session was recorded without the therapist's or my knowledge or consent."

As we previously reported, the entertainment world was left stunned after TMZ published an audio recording of Collins -- most well-known for his role as the beloved Rev. Eric Camden on '7th Heaven' -- seemingly confessing to molesting several young girls in the past.

"On the recording, I described events that took place 20, 32, and 40 years ago," the actor continued. "The publication of the recording has resulted in assumptions and innuendos about what I did that go far beyond what actually occurred. As difficult as this is, I want people to know the truth."

PEOPLE reports that Collins' full statement -- in which he describes "in vivid detail" how there were three victims from 1974 to 1994 -- will be printed in the magazine's upcoming issue, on stands this Friday, Dec. 19. Collins will also sit for a lengthy interview with Katie Couric, which will air on ABC's '20/20' on Friday as well.

The actor also said that he has "agonized" over the decision to apologize to his victims.

"I did have an opportunity to do so with one of the women, 15 years later. I apologized and she was extraordinarily gracious," he stated. "But after I learned in the course of my treatment that my being direct about such matters could actually make things worse for them by opening old wounds, I have not approached the other two women, one of whom is now in her 50s and the other in her 30s."

As for the understandable terror that such abuse could happen again, Collins said that he has "not had an impulse to act out in any such way" in 20 years.