Joel Andrew Bilston appeared in the dock of the County Court at Ballarat on Thursday over the April 8 incident.

He pleaded guilty to five charges, including aggravated burglary, unlawful assault, committing an indictable offence while on bail and contravening a family violence intervention order.

Crown prosecutor Danielle Guesdon said police arrested Bilston on April 8 following an incident at the Delacombe address.

She said Bilston smashed a window and gained entry to the house via a door before he grabbed his former partner and smacked her face.

Bilston was bailed with the condition he not commit family violence against his former partner.

Police officers accompanied Bilston to the house at 8.30pm so he could collect his property, but he returned an hour later on his own.

Ms Guesdon said Bilston's former partner was walking down the hallway when she saw Bilston, who grabbed her and pushed her to the floor.

She said Bilston saw his former partner's friend sitting in her bedroom and Bilston punched him multiple times to the head.

"He picked up a screwdriver and said, 'You are lucky I have not put holes in you yet'," Ms Guesdon said.

The court was told the man was taken to Ballarat Health Services Base Hospital but was later released.

Police located Bilston at his mother's Wendouree house the following day. He told police he had attended his former partner's address on April 8.

The court was told Bilston knew his former partner would be at the house on the night in question, but did not know a man would also be there and he "reacted very poorly".

Bilston had been in an on-again and off-again relationship with his former partner for five years and they had been living in Delacombe together with their son.

He occasionally stayed at the house but only if his former partner gave him permission to do so.

Bilston's defence barrister said her client was not intellectually disabled but he was just above the IQ level of a person with a disability.

"He still struggles day-to-day with planning for the future, having foresight and complying with court orders," the defence barrister said.

But she said Bilston had a willingness to engage. Judge Duncan Allen ordered a pre-sentence report to be prepared. Bilston will reappear at the County Court on January 28 for a further plea hearing.

Bilston, whose mother supported him in court, has been in custody for 191 days.

- Family violence: 1800 RESPECT

- Relationships Australia: 1800 050 321