(CNN) It's been 70 years since Robert says he was sexually abused by a priest. And in the decades since, his wife and family suffered every day.

"I couldn't show any affection with my wife," said Robert, now 83. "My children, I couldn't hold or hug."

This is the kind of lifelong trauma endured by hundreds of victims at the hands of Pennsylvania priests.

Robert has been waiting seven decades for priests to be held accountable.

In a scathing, 887-page report, a grand jury said more than 300 "predator priests" have been credibly accused of sexually abusing more than 1,000 child victims.

"We believe that the real number of children whose records were lost or who were afraid ever to come forward is in the thousands," the grand jury report says.

The report investigates clergy sexual abuse dating back to 1947 in six Pennsylvania dioceses.

Robert's case was one of the earliest. It took place when he was about 13 years old, back when Harry S. Truman was President. That's what made it especially difficult to tell anyone.

"Who would have believed me? (That) a priest, in 1948 or '47, would abuse you or do that?" Robert said.

"No one ever heard of such a thing because they covered it up."

Robert said he believes he was preyed upon because he didn't have a father -- something his abuser could take advantage of.

"They targeted me because I was fatherless," he said.

Robert shared his story in a video shown at a news conference Tuesday announcing the grand jury's report.

The investigation revealed many other horror stories, including:

-- A case in which one priest fondled and masturbated a young teenage boy "under the pretext of showing the victim how to check for cancer."

-- An HIV-positive priest who abused children for years before going to prison.

-- A priest who allegedly abused several boys but was still given a recommendation to work at Disney World.

"As a body of bishops, we are shamed by and sorry for the sins and omissions by Catholic priests and Catholic bishops," said Cardinal Daniel DiNardo, president of the US Conference of Catholic Bishops, and Bishop Timothy L. Doherty, chair of the bishops' Committee for the Protection of Children and Young People, in a statement.

The Vatican declined to comment on the grand jury's findings.

Mike McDonnell, a victim who appeared Thursday on CNN's "New Day," said he loved going to church with his parents but was abused by two priests when he was 11 years old. It took him decades to face the truth about what happened.

The abuse affected his marriages, caused substance abuse and destroyed his belief in the Catholic Church, said McDonnell, who publicly has accused and sued two priests in the Diocese of Philadelphia, which was not covered by the latest grand jury report. One of those accused priests was defrocked, while the other was removed from public ministry, diocesan records show

"They stole the most sacred thing I had, and that was my Catholic Church," he said.

McDonnell said he wasn't not surprised the Vatican hasn't responded.

"This is Roman Catholic Church, playbook page 82. This is what they do -- they hide, they are deceitful in what they do. It is self-seeking," he said. "And they're going to spin every story."

Carolyn, another victim who spoke in the grand jury video, said she first met her abuser when she was about 18 months old.

"I was in my diaper, and I ran out, and ran right to him," Carolyn said, choking back tears.

As she got older, "he would always have his hands on me," said the woman, now 37.

And whenever she hears the word "God," Carolyn said, flashbacks of abuse keep coming back.

"The word 'God' makes me think of him," she said. "I just feel like my whole life has been a lie."

Even though Carolyn's alleged abuse happened decades after Robert's, she said it was still incredibly difficult to speak up.

"It's very lonely, especially when it's your word against God's," she said.

But that loneliness is subsiding after the grand jury's report.

"I think this report's going to help people who don't have a family, because they're going to know that there's a lot of people out there now that believe them and are behind them," she said.

And although Robert's been waiting 70 years for this kind of vindication, he said he knew it would happen.

"I just was always saying, 'They're not going to beat me.'"