The former Pop Idol winner was attacked by Derek McArthur outside the Linen pub in Glasgow’s Shawlands in January 2017.
Michelle said she was left injured and an “absolute wreck” after the incident.
The 38 year-old stated: “I was hysterical and terrified. I could not believe it had happened.”
McArthur was fined £350 after being found guilty of assault at a trial at Glasgow’s Justice of the Peace Court.
The 41 year-old had denied the charge claiming he had been acting in self defence.
He said Michelle’s husband Jeff Nimmo had punched him after asking: “Why did you grab my missus’ t***.”
Michelle had been out with her husband and others on January 21 2017 to celebrate a friend’s birthday. They later ended up in Michelle’s local pub Linen.
McArthur- who often performed there - was also in the bar that night.
The court heard McArthur had at one point accidentally fallen into the singer’s chest after playing on a skateboard.
Michelle and her group later left the bar in the early hours. She then recalled being outside when McArthur came towards her “at speed”.
Michelle told prosecutor John Bedford “He was absolutely incensed – screaming in my face.
“He was totally incoherent. He then had his guitar case and battered me with it.”
She remembered being hit once down the left hand side of her face and falling to the ground.
Michelle said “He had been furious. I don’t know why. It all happened so quickly.”
The court heard witnesses tried to stop McArthur, but he fled the scene.
Michelle added: “I was hysterical, absolutely terrified. I was in total devastation, as anyone would be.”
She later made an appeal on Twitter to try and trace McArthur.
The trial was told Michelle did not leave the house for days until her husband urged her to see a doctor.
She was put on medication describing herself as an “absolute wreck”.
Michelle said: “I still believe there was no rhyme nor reason for this. I still don’t know why this happened to me.”
She went on to admit to a “couple of interactions” with McArthur prior to the alleged attack.
In 2013 or 2014, Michelle recalled arranging a date with a “nice” man called Des on Tinder.
This person then failed to show – but got in touch again urging her to meet.
Michelle remembered this man soon becoming “aggressive” and she cut any contact.
Around a year later, Michelle was in Linen when a man hosting an open mic singing night apparently made a jibe directed at her.
The remark was: “Don’t you hate it when talentless people win talent shows and there are real musicians like me.”
Michelle spoke to the bar’s manager – who went on to tell her the entertainer and this man had previously “gone out” with each other.
Michelle: “It was then I realised it was the man on Tinder.”
She later denied claims of “lying to protect” her husband Jeff.
Andy Aitken, defending, suggested Jeff had punched McArthur outside the pub that night.
It was claimed McArthur had then accidentally hit Michelle with his Fred Perry bag as he tried to defend himself.
But, the singer replied: “I can categorically state 100% that did not happen.”
Jeff also denied in court attacking McArthur.
Mr Aitken suggested he had punched the musician after his wife had been called a “fat b******.”
Jeff replied: “No. I regret my wife was attacked and I could not protect her.”
McArthur – who said he is friends with indie band Ocean Colour Scene – stated the allegations had left him needing counselling.
Denying the assault, he added: “I cannot go down the street without people laughing at me.
“For people to think I have hit a woman destroys me.”
He claimed Jeff had hit him after he stated to him: “Why did you grab my missus t***.”
McArthur, also of Shawlands, said Michelle then done the “most calculated thing” he had seen by insisting he had hit her.