Mr Gilmore admitted he had been rude and arrogant at the hotel restaurant, but he denied any other wrong-doing, in response to allegations that he had behaved sleazily to women at his table.
Mr Gilmore said he had an argument with the waiter after he was not allowed another bottle of wine.
He said that as an MP he had a good grasp of liquor laws and believed the waiter was not right to refuse him alcohol because he was not drunk.
Mr Gilmore said he had only consumed three glasses of wine and two beers at the restaurant.
Asked whether lawyer Andrew Riches had lied in his statement about the events that occurred that evening, he said: "The words that Mr Riches used were not the words that I used."
He said that Mr Riches had consumed "as much to drink if not more than I".
He said that no service industry worker deserved to be treated badly.
"I crossed the line, and it will not happen again."
Asked whether he was a bully, he said he was a "strong-willed person and personality".
The MP denied threatening to use the Prime Minister's office to sack a waiter.
He said that the waiter did not know who he was. Mr Gilmore presented a business card and the waiter asked if he knew the Prime Minister, he said.
He believed he still had a contribution to make to Parliament.
"If there's one thing that I've learnt, it's that I need to operate my life with far more dignity, humility and grace."
Mr Gilmore became teary when he spoke of the week of "hell" he and his family had been through since the incident.
In a written statement, Mr Gilmore said he was proud to be an MP and in awe of his colleagues.
"However I am not proud of my actions that occurred on Saturday, April 27."
Mr Gilmore had previously issued an apology on Facebook, Twitter and sent a written statement to journalists.
Key is standing beside his apologetic MP, but warned it was unacceptable for anyone to abuse hospitality staff.
Mr Key made the comments this morning on his way to caucus where Mr Gilmore was due to get a dressing down by his National Party colleagues after he abused a barman at a Hanmer hotel when he was denied another bottle of wine.
Mr Key said Mr Gilmore would have to earn the respect of the New Zealand public.
"The expectation of MPs, rightfully so, is that they adhere to a high level of behaviour and I think on the occasion of that Saturday night he let himself down.
"He will continue to have my support as a Member of Parliament and a member of my caucus.''
"He's got some work to do on behalf of the New Zealand public that he has got a good contribution to make - I think he can do that.
"He will need to go out and earn that respect.
"... he will also be well and truly aware ... of my expectations, and that is that he goes out and treats people with full respect ..." Mr Key said.
Justice Minister Judith Collins said sometimes people do stupid things; particularly under the influence of too much alcohol.
Ms Collins acknowledged Mr Gilmore's apology.
"I will say that most of us can think of lots of people who have made compete tits of themselves when they've had far too much to drink."
She said she could remember the time an MP used a hallway in a hotel as a urinal.
The Hanmer Springs Heritage hotel - where the incident occurred last week - said it would not lodge a complaint.
