Daryl Rivett repeatedly punched a man in the head and left him for dead off a Melbourne road after accusing him of having an affair.
Lamin "Lee" Mastertom-Bojang, 53, died in hospital three days after paramedics found him unconscious in shrubs at Frankston in December 2019.
Rivett had drunk a five-litre cask of wine before going to his ex-partner's squat house, where she was drinking and talking with Mr Mastertom-Bojang.
"I know you two are screwing," Rivett said.
Mr Mastertom-Bojang replied: "I love you bro. I wouldn't do this to you bro".
They left the squat before Rivett punched Mr Mastertom-Bojang four times as the man held his hands up.
He fell to the road, hitting his head.
Rivett, 54, dragged him into shrubs and waited for more than an hour before using a payphone to call triple-zero.
He left but later turned himself in to police and went on to plead guilty to manslaughter.
Mr Mastertom-Bojang's partner sobbed as she told Victoria's Supreme Court on Thursday "I close my eyes and see Lamin lying in pain".
"Our relationship was one of dignity and wanting a better world and doing things to make this happen."
Mr Mastertom-Bojang's ex-wife, Kate, told the court "Lamin has become another black man killed for no apparent reason".
She added their sons no longer had a connection to their Gambian heritage.
"They have not only lost their father at the young age of 10 and eight, they have also lost the blackness of their identity," Ms Mastertom-Bojang said.
"They now only have a white mother."
Acting for Rivett, Pardeep Tiwana said his client had been trying to protect and not hide Mr Mastertom-Bojang by dragging him off the road and into bushes.
He had only waited before calling triple-zero because he'd never used a payphone before and went looking for his mobile phone, the barrister said.
Rivett's life was one of trauma and depravation. Of Aboriginal background, he lived in a campsite on the Seaford foreshore.
Growing up, his father hit him regularly and he'd run away to escape the abuse.
He started drinking at 13 and also went on to use ice. He also tried to commit suicide while on a school camp.
Rivett left school in year 10 and hadn't worked since 1995. He has numerous convictions, including for assaulting a police officer.
He vaguely remembered saying something about his ex-partner and Mr Mastertom-Bojang being intimate before the fatal attack.
But he said he did not mean to seriously hurt the man, let alone kill him.
Rivett is due to be sentenced on August 31.
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Australian Associated Press