ROME -- A founding member of a three-year-old commission set up by Pope Francis to protect minors from sexual abuse in the Catholic Church has quit, accusing the Vatican of “stonewalling” the commission.

As CBS News correspondent Seth Doane reports, it is a very public blow to the Vatican on a very sensitive issue, and at the center of it all is a victim of sex abuse who says there’s cultural resistance to change in the church.

“My feeling was, at this point, it was better for me to come out and speak about it because these men thrive on silence and cover-up,” Marie Collins told CBS News on Thursday morning at her home in Dublin, Ireland. “I felt I could do more outside than inside.”

Collins, who was sexually abused by a priest at the age of 13, had grown tired of what she says were “constant setbacks” in her work on the panel set up by Francis to protect minors.

“To find that there’s still a group of men in this level of the church who do not see child protection as a priority, that do not get it in 2017, is just unacceptable,” she said.

In her resignation letter Collins said she believes Pope Francis is “sincere” in his efforts, but the “resistance by some members of the Vatican Curia (the central administration), “has been shameful.”

Monseigneur Anthony Figueiredo is a CBS News consultant on the Catholic Church, and asked by Doane whether Americans might hear in Collins’ resignation letter a message that the Catholic Church still is not serious about dealing with this issue of sex abuse, he was adamant: “It’s very, very serious -- perhaps more than any other organization in the world the Catholic Church has taken this on board.”

“We all know that perhaps the hardest thing to change is not a structure of an organization, but it’s the very attitudes of certain people,” Figueiredo said. He suggested Collins might be speaking out now, “because she knows this Holy Father will now do something.”

Boston Cardinal Sean O’Malley, who heads the commission, said in a statement: “We will certainly listen carefully to all that Marie wishes to share with us about her concerns.”

The only other sex abuse victim on the panel, Peter Saunders, also became critical of it and was forced out last year.