James Michael South, 34, yelled "who the f--- are you" before punching the man in the nose, lip and top of his head, causing his scalp to split and blood to drip down his face.

Tendered court documents showed South and the woman had been in a relationship for almost a year and mutually decided to spend time apart.

On the morning of September 10 last year, South took a coffee to the woman's home and knocked on the door, before finding another man standing beside her bed, prompting South to yell "who the f--- are you?"

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The woman stood between South and the other man, until she asked South to leave. However the men got into a scuffle, with South punching the man several times, causing his head to bleed.

"Stop, stop, get out!" the woman yelled. South yelled back at the man, "this is my f---ing missus, you f---!" as he began to film the incident.

He left the home but returned shortly after with a male associate. The woman threatened to call triple-0, asking him to leave again, however South snatched the phone and threw it.

South and the man left, with South uploading the video he took to social media. Police arrested him about 1pm that day.

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In court, South pleaded guilty to assault and intimidation. Defence lawyer Matt Ward said his client faced recent "devastation in his life" prior to the incident, adding that his offending wasn't premeditated or planned.

Magistrate Claire Girotto said South's reaction was "understandable" but denounced the behaviour that followed.

"Seeing another man there, you would be startled and angry, but you don't beat someone up," she said.

South was handed a two-year community correction order.

Read more Illawarra court and crime stories here.

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