S inead O'Connor's fourth marriage is over, a mere 16 days after it began in the back of a pink Cadillac. The "Nothing Compares 2 U" singer ended things with therapist Barry Herridge on Christmas Eve, she announced in a lengthy message on her website.

O'Connor explains that her husband had been "terribly unhappy" and that their relationship had caused much anguish in his family and posed a threat to his work as a child therapist, and so she decided it would be best to cut her losses and set him "free."

"I'm sorry I'm not a more regular woman," she writes. "I truly believe, though it is painful to admit, we made a mistake rushing into getting married, for altruistic reasons, and weren't aware or prepared for the consequences on my husband's life and the lives of those close to him."

She adds, bluntly, that she broke up with him because "I think he is too nice to do so. And too nice to trap." They lived together for only seven days, she says. "We haven't been awful to each other. So while I feel sad for my husband, and sad to be the cause of sorrow to yet another poor man, I'm also happy that I know we weren't horrible to each other and he is better off free."

In her post, O'Connor pleads with the media to take a hands-off approach to Herridge. "Publicity over all this could jeopardise (sic) his job. Please, don't do that to him. or I will have that on my conscience as well. he is a private person. I'm fair game. He or his family are not."

O'Connor and Herridge tied the knot on Dec. 8, her 45th birthday, in a drive-thru ceremony in Las Vegas. After filling out the paperwork, the couple shared vows from the back of a light pink Cadillac at A Little White Wedding Chapel while O'Connor donned a matching pink wedding dress.

The two met during the singer's online search for a "wham-bam" sexual partner that drew much media attention several months ago.

This was O'Connor's fourth marriage. Her third, to Steve Cooney, ended in divorce earlier this year. The mother of four was also previously married to producer John Reynolds and journalist Nicholas Sommerlad.