"I have caused my wife and children harm, shame, humiliation," he told Campbell Live last night.
Public relations experts say the sex scandal may not spell the end of his career and that his future will depend on how well he handles the issue and the level of support he receives from his family .
Messages have flooded Mr Brown's Facebook page and a poll on nzherald.co.nz today showed 57 per cent of more than 30,000 respondents believed he should stand down.
Among the messages on Facebook, Stephen Holley said: "He has abused the position of mayor and the power that comes with it to gratify his own sexual desires, just wish this had come out before the election as I reckon more folk would have voted against him!"
In a statement, Mr Brown said he had told his wife - to whom he has been married for more than 20 years - about the affair. Last night, he said he told her last week.
The affair is believed to have started in mid-2011, about a year after Mr Brown's wife was treated for throat cancer.
Ms Chuang, 32, has sworn an affidavit and says she has text messages to back up her claims, according to the report on the Whale Oil site.
Mr Brown's wife Shan Inglis this morning appeared to be trying to get on with her everyday routine following the revelations of her husband's affair.
She bundled two daughters into her car to take them to school this morning from the family's home in Totara Park, Manukau.
Mr Brown arrived at the Auckland Town Hall at 9.20am, his mayoral car diverting from its usual parking spot on Queen St to the underground Civic carpark.
Mr Brown made a swift exit to a backdoor entrance to the Town Hall, telling media "it's good to see you" but declining to answer any other questions.
He is expected to spend much of today meeting councillors to discuss their plans as he prepares to tweak the council committee structure and consider appointments.
