The Boston Archdiocese (search) will lose 65 of its 357 parishes, a massive restructuring brought on partly by the clergy sex abuse scandal (search) that aggravated already shrinking Mass attendance and weekly collections.

Archbishop Sean O'Malley (search) announced the parish closings Tuesday, completing a process that began in December when he said the Roman Catholic archdiocese would be forced to undergo a major downsizing.

He said the reduction was needed because of declining Mass attendance, a shortage of priests and the inability of the archdiocese to support struggling parishes in the midst of a financial crisis caused in part by the abuse crisis.

The announcement was dreaded by parishioners and pastors, who received word about the fate of their churches in letters from O'Malley delivered Tuesday morning, just hours before he released the complete list of closings during a news conference.

The parishes will not close immediately but will gradually shutter through the end of the year.

Seventy parishes in all will be affected by the downsizing, but five new parishes are being created through mergers. Another five churches will remain open as worship sites, though they'll be maintained by neighboring parishes and their membership will be merged with those existing congregations, O'Malley said.

At St. Susanna Parish in Dedham, some parishioners gasped and others cried while the pastor, the Rev. Stephen Josoma, announced that the church would close.

"I feel like we've been betrayed," said Bob Frasca, 74, a retiree who has attended the church since it opened 42 years ago. "I will not give another dime to the archdiocese."

Josoma immediately told the group of about 80 parishioners who gathered in the parish hall that he would appeal the decision to close the church, which has about 800 member families.

After a lengthy review process, the names of 143 churches were submitted to O'Malley for possible closure. The archbishop made the final decision on which parishes to close after consulting with a panel of priests and bishops.

The Rev. Christopher Coyne, a spokesman for the archdiocese, said O'Malley tried to give parishioners as much input as possible into the decisions by asking leaders within geographic clusters throughout the archdiocese to hold meetings and submit recommendations on one or two churches to close within their cluster.

Parishes on the list to be closed may appeal to O'Malley. If they fail to change his mind, they can then appeal to the Vatican, but only on procedural grounds, not simply on their belief that their church should remain open, Coyne said.