A court on Thursday backed claims that Ian Stevenson deliberately squeezed the woman’s breast at a care home in Co Antrim before joking that he would “grope anything”.
District Judge Amanda Henderson said: “I found the injured party to be credible in her testimony.”
Stevenson, a 49-year-old nurse and former mayor of Ballymoney, will now be sentenced next month.
Belfast Magistrates’ Court heard he allegedly asked for a hug while talking to the woman on a corridor in April 2017.
Linfield v Portadown Sunday clash: Breakers of the Sabbath will answer to God
NI Weather: 45 pictures of how we enjoyed wall-to-wall sunshine
Thousands expected to take part in 'Derry Day' this weekend
Esmond Birnie: The protocol is not as claimed boosting growth in Northern Ireland
Tom Topping: Heartbroken daughter says ‘world is totally shattered’ after father’s shock death - funeral details released
She claimed that after raising her arms Stevenson, of Headlands Avenue in Ballymoney, grabbed her breast.
“He actually squeezed when he did it,” the woman said in evidence.
During the trial she described responding by pushing him away and telling him “no”, adding that the encounter left her shocked and frightened.
“He just basically tried to laugh it off and made the joke ‘You know me, I would grope anything... well, not anything’,” the woman claimed.
The court was told she later sent Stevenson a Facebook message, expressing her “disgust” at what allegedly happened.
Asked how the incident has affected her, she replied: “It makes me nervous that somebody in that position could take such an advantage.”
With Stevenson emphatically denying the sexual assault charge, it was put it to the woman that her allegations were inconsistent and false.
Defence counsel argued it was unbelievable that a public figure and nurse of 22 years standing would carry out the alleged act in the middle of a care home.
It emerged in court that Stevenson has since been dismissed from his nursing position - an action which is to be challenged at a tribunal.
The defendant, a representative on Causeway Coast and Glens Borough Council, has also reportedly been suspended by the DUP pending the outcome of the case.
He claimed it was the woman who offered him a hug when he told her he was going to lay a wreath on a friend’s grave.
At no point did he grab or touch her breast, he insisted.
Questioned about his alleged comments, he told the court: “Anybody that knows me, anybody in the political sphere, knows that I have never cursed in my life, which might seem a bit incredible, and I certainly would not say anything like that.”
Stevenson rejected prosecution contentions that he “took a chance” by overstepping the boundaries and grabbing the woman’s breast.
“It’s not my nature, it’s not me,” he maintained.
But delivering judgment on Thursday, Mrs Henderson said the woman’s testimony was consistent with her complaint following the alleged incident.
The content of her Facebook message also supported her assertion of sexual touching, the judge held.
She said Stevenson had failed to provide an explanation for why the woman would fabricate the incident after they had previously been on good terms.
Accepting he had allegedly remarked that he would “grope anything”, Mrs Henderson confirmed: “He did the act deliberately and I convict.”
Stevenson will return to court in four weeks’ time to be sentenced.