"It would be very arrogant of me to think I was not somehow part of the problem; that perhaps I didn't do this correctly," O'Donnell said.
Mallette has also chimed in on O'Donnell, calling him arrogant and even a bully, WLS reported. When asked about his successor during one interview, Mallette reportedly broke into a rendition of the folk song "Plastic Jesus."
O'Donnell has not responded to a request for comment.
Parents and parishioners at St Margaret's, many of whom say they have known and been helped by Mallette for years, gathered to meet on the matter Tuesday night. Some have had their confidence in the parish shaken by recent events.
"It's shaken me, but I'm not going to run," parishioner Tonetta Oliver said.
Harris told ABC News that he believes the most disheartening thing about the situation at St. Margaret's is that all the church and school's families and students are being affected by the internal strife.
"All of our lives are altered, and we're trying to put the pieces back together," he said. "It's been very painful and difficult. But we're people of faith."