A man who stabbed his ex-girlfriend 78 times has told a judge he loved her and was sorry for what he had done.

“I write this letter with remorse and I know that no words can undo the pain and devastation caused by my actions in 2022 when the life of someone I genuinely loved was tragically ended,” Thompson, 25, wrote.

He said he cared deeply for Anderson and his love for her never faded despite the relationship being “very toxic”.

“My memory is unclear on every detail of what happened and that’s something I struggle with constantly,” he wrote.

“What I do know is that I never planned to hurt her that night.”

Thompson claimed they had struggled with a knife and when his hand was cut “something inside me lost control”.

“I have asked myself a thousand times since then how it could have gone so wrong.

“I would give anything, truly anything, to take that moment back.”

Thompson said he took responsibility for what he had done even if he wasn’t in a rational state of mind at the time.

He claimed he now saw there were many opportunities “in those short seconds” to prevent the murder.

“I know I will carry this guilt and shame with me for the rest of my life as I can’t reverse what happened no matter how much I wish I could.”

Justice Weinstein said he was happy to receive Thompson’s letter because it was the first time he had seen remorse from the killer.

The judge said it appeared Thompson, who stabbed Anderson 78 times with two kitchen knives over two minutes, had a longstanding diagnosis of schizoaffective disorder, a mental illness characterised by schizophrenia and a mood disorder.

Thompson’s current diagnosis involved a mixture of post traumatic stress disorder with a severe personality disorder.

Justice Weinstein said Thompson’s mental illness was complex and it appeared his moral culpability for the brutal murder might be diminished to some extent because of it.

Thompson, 25, had been due to stand trial for murder before pleading guilty earlier in April.

Thompson killed Anderson 16 days after his release on parole after being jailed for serious domestic violence offences against her.

Anderson’s mother, Tabitha Acret, had told the court in an emotional victim impact statement on Monday how her daughter must have suffered a “fear no human should ever know” on the night she was murdered.

“Mackenzie was convinced Tyrone would murder her on his [parole] release. She was in fear all the time,” Acret said.

Thompson broke into Anderson’s apartment in the Newcastle suburb of Mayfield on March 25, 2022.

A male friend who had gone to her aid for a second time during the night looked through a gap in her blocked door and saw her lying on the ground with Thompson standing over her repeatedly stabbing her.

Thompson was not saying a word.

Police arrived and found Anderson unconscious with stab wounds to her face and body. A broken knife handle lay on top of the left side of her chest.

Thompson has been in custody since his arrest in March 2022.

Readers seeking support can contact Lifeline on 13 11 14 or beyond blue on 1300 22 4636.