Joshua Michals, 26, is on trial at the Old Bailey for the murder of 31-year-old Zhe Wang, who was a fellow student at Goldsmiths, University of London.
On March 20 last year, Ms Wang was found with two stab wounds to her face at her flat in Manor Park after the defendant called 999, the Old Bailey has heard.
Giving evidence on Monday, Michals said he had put his hands around her neck to try to restrain her because she was trying to attack him.
He insisted he did not mean to kill her, cause her serious harm – or any harm at all.
Brian St Louis KC, defending, asked: “What do you think would have happened if you hadn’t managed to get the knife out of Ms Wang’s hand?”
Michals replied: “I think she would have tried to kill me. She just wouldn’t stop the attack. She just wouldn’t stop.”
He told jurors that he felt he had no choice when he struck her with the knife to “make her stop”.
Born and raised in Chicago, Michals studied film making at university before coming to London to pursue a year-long masters degree at Goldsmiths.
The younger of two siblings, Michals told jurors that his father was the vice president of sales at his company and his mother was a graphic designer and photographer.
On his decision to study in London, the aspiring film maker told jurors: “It seemed like an exciting opportunity to study abroad to pursue a masters. It seemed like the right thing to do.
“Me and my mum were looking at things in the London area and we ended up with Goldsmiths.”
Michals said that he met creative writing student Ms Wang he went to Goldsmiths to enrol and pick up his student identification, and they got on “really well” and exchanged numbers.
They began to exchange text messages and went on to “hang out” nine or 10 times in the months before her death, the court heard.
Michals said that they did not introduce each other to any of their friends because Ms Wang wanted to keep the relationship between them.
He told jurors: “She was quite private and I respected that.”
Ms Wang appeared to be looking for a life partner with a “spiritual resonance”, but Michals told jurors that he had wanted to keep it casual.
When they met in October and November 2023, they engaged in “kissing and cuddling”, he said.
Ms Wang asked to see test results confirming he did not have a sexually transmitted disease before taking things further, jurors heard.
When Ms Wang visited him at his flat, she insisted on cleaning his couch before she would sit on it, the court was told.
Michals said: “She sprayed the couch, the bathroom, started wiping down the surfaces, the counter tops, bathroom, sink, anything she thought she might touch.”
He thought it was “a little bizarre” but he did not want to make a “big thing of it”, he said.
Michals said he was feeling “so-so” about pursing the relationship, telling jurors: “We got along really well, the conversation was really fun.
“The germophobia was a bit much at times. I didn’t quite understand it. It was just bizarre.”
He said that her cleaning seemed “excessive” and the phobia appeared to get “much worse”.
After meeting on November 4 2023, they did not see each other again until February 23 2024 when they first had sex.
Michals described Ms Wang as a “very sweet, warm, bubbly” person.
It came as a surprise when he found out during the legal process that someone else had said they were in a relationship with her too, he said.
“I didn’t think it was real at first. I thought it was someone else’s legal papers. I just didn’t think that was something she would do.”
The defendant told jurors Ms Wang was against having children, saying: “I thought most people had a positive outlook about having kids. I don’t think I had heard anybody say they hate babies prior to her.”
The court heard that Michals had never been in trouble with police before, and had never contracted a sexually transmitted disease or suffered from any mental health issues in his life.
Michals, of Deals Gateway, has denied murder and the Old Bailey trial continues.
He had faced trial at Woolwich Crown Court last year but the jury was discharged to allow additional witness evidence to be heard.
