To some extent, she said, her life is still defined by abuse as a child at the hands of her mother. She and her siblings were “beaten up very severely with every kind of implement you can imagine,” she told Spin magazine in 1991, and told they were dirty and worthless. “Merely the sounds of my mother’s feet,” she said, “were enough to send us into spasms of complete terror.” In 2007 she told Oprah Winfrey that she had bipolar disorder. “But that was misdiagnosed,” she said now. “What I have is post-traumatic stress from that abuse, that I deal with a day at a time.”

She dealt with those issues in public after her hit Prince song, “Nothing Compares 2 U,” topped American and British charts in 1990, making her a bona-fide star and shaven-headed idol to many women. Her 1990 album, “I Do Not Want What I Haven’t Got” (Ensign/Chrysalis), sold millions. But in later years she announced a form of retirement from pop music, put out experiments in traditional Irish folk and reggae and learned bel canto. She returned to Ireland, after stints in London and Los Angeles, “so my children can be near their fathers,” she said.

When she took to her blog and to Twitter last year, she said, she had come to terms with who she was. Ms. O’Connor said, “Musicians were sent to earth to help people, so we have to be imperfect, or how will they identify with us?” She had, she said, “adopted a policy of not acting any differently to my next-door neighbor.”

Her manager, Fachtna O’Ceallaigh, who has known her for nearly 25 years, said that he knew he would not, could not, stop her from expressing herself. “So I just tried to look away and think of all the things she has achieved with that same openness, like risking her career taking on the Catholic Church,” he said. “The same thing that makes her great, that generates joy and fulfillment in her work, has also caused great pain and difficulty for her. It is incredibly painful to see her living her life the way she lives it sometimes.”

In the dark days at the start of January, Ms. O’Connor said, she was cast into despair by an Irish newspaper that used her words online to target her husband. “It is a goldfish bowl,” she explained, “and I can’t get away from being me. Even in the nuthouse, they were afraid to take me in, because I’m Sinead O’Connor.”

She wants the same things as everyone else: a happy relationship, contented children, a blooming career. “I want to be like any other person, but I’ll have to accept that I can’t be, because sometimes me being me hurts other people,” she said. As visitors left her home, she gave wide-open, un-self-conscious hugs of farewell. In the days following the interview she text-messaged a reporter new thoughts that had occurred to her, impolitic or not. But her new Twitter account is locked and accessible only to those she knows.

“It’s not fun anymore,” she said during the interview. No one who judges her, she said in a text message, has “any inkling of the level of loneliness which would lead” to her missteps. But she will stick to her vow not to overshare online because, she wrote in another message, she wants to be known only for two things she remains proud of: “making music and fighting the Vatican.” Nothing more.