"The only thing that fuelled me to write it was the thought that only a lunatic would read it, so what had I got to lose?" she says. Even the title, Are You Somebody?, hints at a fragile sense of disbelief. "I wanted a small print run because I was so ashamed about how many would be left over. In the end, he said he couldn't do less than 3,000." They settled on 5,000.
Then, just as her book reached the shops, she appeared on Ireland's television institution The Late Late Show, and within five hours every copy had been sold. Published last autumn, it has sold over 70,000 copies, topping the best-seller lists in Ireland for more than five months. It will be published in Britain this week.
On one level, the book is an account of her life, from childhood as one of nine children, through university in Dublin and England, to her career in the media. On another, it is a candid examination of her disappointments in relationships, finally having to confront middle-age alone. She is in her mid-fifties.
Now, women stop her in the street and want to confide in her, she says. They write long, painful letters about their own disappointments. This week, a woman ran up to O'Faolain and told her that, after reading the book, she could finally admit to her parents that her marriage was over.
There is a price to pay for opening up her personal life - for one, her public role is quite confusing. "I'm still supposed to be a pundit whose thoughts on EMU and Sinn Fein are worthy, but I live in a kind of Oprah Winfrey world where, everywhere I go, people try to touch me."
Perhaps it is O'Faolain's engaging honesty that has compelled readers to share their emotions and identify with her situation. She exposes areas of pain in her personal life many of us would wish to conceal. "I think there is some note in it that I never knew I was sounding. It does speak out, especially to women, about hope disappointed and finding life hard to live."
This certainly explains why her book has struck such a chord of sympathy, despite the fact that, on the surface, her story isn't that tragic. O'Faolain agrees: "No, I know. Nothing that awful happens to me. In some ways it's been a grand life. You could turn it around and say, 'What's wrong with her? She's fine.' "
Yes, there was the miserable childhood that clearly influenced her life - her mother was an alcoholic and her father (also a journalist) mostly indifferent to his family's needs. But there are early signs of strength and independence. She saved herself through a love of reading. Books offered emotional escapism as well as a fast track out of an unhappy upbringing. She won a scholarship to boarding school then a place at University College Dublin. There was further study at Hull and Oxford, after which she trained and worked in London as a BBC producer.
It is at this point that her memoirs begin: "The man who had absorbed me for 10 years, and who I had once been going to marry, had finally left... I knew he wouldn't come back and I didn't want him to." Depressed and drinking too much, she returns to Dublin and continues working. Finally, she gives up the booze and fags and lands her column on the Irish Times.
In many ways, O'Faolain is the prototype thirtysomething female singleton who is now a media celebrity. Like Helen Fielding's Bridget Jones, she had a good job in TV, smoked and drank too much and is still conscious of her weight. ("I've seen 16 skinny girls walk past this morning," she exclaims. "How long is it since you've seen a stomach like this?" she says, patting her own.)
More importantly, O'Faolain assumes that at some point she would step into the conventional milieu of a partner and children - yet it still eludes her. "I come out of a past that most young women wouldn't know," she says. "But, like me, many of them are trying to work out the pattern of their life and how to make the most of their freedom."
Not that she denies the fear of facing middle age alone - at one point her mood shifts visibly when she says, "It is hard at this age. I hope when I'm older I'll at last fit into my own skin," and suddenly her eyes fill with tears.
In this sense, O'Faolain's confessional could have slipped into self- pity, but, in person at least, she manages to by-pass maudlin indulgence. "It can be wonderful on your own. I come back after a day out, order a pizza, open a bottle of wine and read a book. It's really the deepest pleasure." Spoken like a true lone ranger.
8 'Are You Somebody: The Life and Times of Nuala O'Faolain', published by Sceptre on 18 September.