Nathan Galvin became obsessed with the size of his manhood after spotting his partner's former boyfriend at a school reunion.
An argument about the former lovers' sex life ensued, during which the aggressive Galvin throttled her in a 20-minute attack and threatened to 'kick her across the kitchen'.
When a judge sentenced the thug to three years in jail, he turned to his crying victim who was in the public gallery of Canterbury Crown Court and made a gun gesture with his fingers towards her, for which he was given an additional four months.
Galvin, 29, was jailed for three years after admitting two assaults on the day of his trial.
He was also branded a danger to women after the court heard four previous lovers and even his sister had been on the receiving end of his violence.
Sentencing Judge Rupert Lowe told him: 'You are a man who has significant problems with women, and a danger to society.
He added Galvin's 'insane jealousy' meant he posed a threat to any woman he was in a relationship with.
The judge continued: 'The risk of you causing serious harm to the next woman you start a relationship with is, on any view, very high.'
Earlier, prosecutor James Cartwright told the court how in October last year Galvin and his girlfriend of 10 months had gone to a school function where one of her ex-partners was also there.
He said: 'The defendant got upset and wanted to know whether the former partner had a bigger penis.
'He grabbed her hair, pulling out some.'
Eight days later, Galvin made similar remarks following another visit to the school, which 'reflected his insecurity'.
He accused her of 'perving over' her ex, and demanded to know whether he performed 'better in bed'.
Mr Cartwright said Galvin then punched his victim in the left ear before putting his hands around her throat and squeezing.
As the victim pleaded with him: 'I can't breathe, I can't breathe', he told her that if she passed out he would 'kick her across the kitchen'.