Christopher Blaikie stabbed Claire Mazzucchi in the neck as she sat eating lunch.
A judge heard how the pair – both studying psychology at Stirling University – had once been flatmates until Miss Mazzucchi felt uneasy living with Blaikie.
The 22-year-old luckily survived the unprovoked attack at Blair Drummond Safari Park near the city.
Blaikie, 24, from Livingston, was held for the stabbing and claimed “homicidal thoughts” had caused him to lash out.
The first offender now faces a lengthy jail-term after he pled guilty to attempted murder at the High Court in Glasgow.
Prosecutor Shirley McKenna told how students from the psychology course were giving a presentation to safari park staff as part of their final-year dissertation.
Blaikie and Miss Mazzucchi were among them.
They had been flatmates, but this stopped when Miss Mazzucci “no longer felt comfortable sharing with him”.
However, Miss McKenna said there were “no issues” between them at the time of the 30 March attack.
The staff and students were later having lunch that day in the safari park canteen.
Blaikie was very quiet and not eating. He then became “inceasingly agitated” and started hammering his cutlery on the table. He then jumped up, marched over to Miss Mazzucchi’s table and stood behind her.
Miss McKenna told the court: “He was seen to put his right hand over her face and wrap his arms around her neck in a headlock position.
“He made two or three stabbing motions [and] stabbed her once in the left-hand side of her neck with a knife.”
As other students realise what had happened, one leaped up and rugby tackled Blaikie. The four-inch blade, which Blaikie brought with him in a rucksack, remained in Miss Mazzucchi’s neck until she pulled it free.
Judge Lord Turnbull deferred sentencing until 18 January in Edinburgh. Since the attack, Blaikie has been diagnosed as having Asperger’s disease.