The discovery that he had been unwittingly caught up in a torrid love triangle pushed a Perth man to breaking point.
A Boxing Day confession from his partner of 15 years sparked a violent outburst from James Smith, Perth Sheriff Court heard.
Despite always maintaining that she had been faithful to him, his former girlfriend admitted that she had been seeing someone else while their relationship was going on.
To make matters worse, the other man was a colleague of both Smith and his ex-partner at a local supermarket and the couple now intended to marry.
The admission of guilt resulted in the 45-year-old lashing out at the woman, grabbing her by the wrist and causing her to fall to the floor.
The court learned that, despite splitting up in October last year, at the time of the assault the couple still lived together at Crieff Road.
Depute fiscal Chris MacIntosh said: “This all arose out of an argument which took place because the complainer had formed another relationship.
“There were tensions in the house because of that.“The accused returned home at about 10pm on December 26 last year and was under the influence of drink. An argument occurred about the new relationship.
“Further tension arose and the accused then assaulted the complainer in the manner libelled.”
Solicitor Erica Watson told the court that her client’s former girlfriend had ended the relationship, but the pair had decided to remain in the same house for the sake of their children.
When Smith returned home from a Boxing Day night out and was met with the shocking confession, he was “very upset” and indicated that he still had feelings for the complainer.
Ms Watson revealed that, in a petty attempt at revenge, her client took mobile phones.
Ms Watson also said that he had not spoken with his former partner since the attack and that she had continued to live in the house they shared.
She continued: “The house is on the market, but he doesn’t know if any offers have been received, because he hasn’t been in touch with her or his solicitor.
“He will not be returning to the family home and the complainer appears to be in a new relationship that would appear to be a serious one.
“Until he discusses matters with her, he is unsure of his position and he remains at a friend’s home.”
Smith, of Brahan Terrace, admitted that on December 26 last year, at Crieff Road, he assaulted the woman by grabbing her by the wrist, so she fell to the ground.
Imposing a fine of £270, Sheriff John Halley said: “I take into account all that has been said, particularly that you have no previous convictions and you committed this offence in sharp circumstances.
“However, you have pled guilty to an assault which is never acceptable or justified.”