But he blamed his meltdown on the torrent of online abuse he received in the wake of his controversial appearance on Celebrity Big Brother.
The Blue singer was handed a £3,325 fine and banned from the roads for two years for failing to provide a specimen and causing £120 of criminal damage.
Ealing Magistrates' Court, in west London, heard the 30-year-old singer had been out partying to celebrate his best friend and bandmate Duncan James's birthday on the night of his arrest.
Officers spotted Ryan swerving erratically at 5.30am on April 11 as he drove his female friend's Audi A3 on the Uxbridge Road in Ealing.
There was an empty bottle in a pocket by the driver's seat and he stank of alcohol.
Majit Mahal, prosecuting, said: "Asked if he had consumed some alcohol that night, Mr Ryan said 'Yes, a few'.
"Officers then noticed that there was an empty bottle in the pocket of the driver's seat." He was in such a "drunken state" that officers took him straight to the police station.
But he refused to take a breath test and in a cell at Acton police station he urinated and was sick all over the floor.