Carl Walker, who is 41, approached the car in Bloxwich High Street on October 27 last year when he saw his ex-wife in the front passenger seat, and began making gestures as if to punch her, a court heard this week.
When the female driver of the car got out to confront him, he began kicking the vehicle, in which two children were also sitting, and went on to smash the rear window with his elbow, prosecutor Mr Dan Tonks told Wolverhampton Magistrates Court.
Mrs Walker said he "appeared angry and intoxicated" and his behaviour made her "believe she would be hit" and "fearful for her life".
Mr Tonks also said that Walker breaking the window sent glass scattering onto the children sitting in the back of the car.
"The most concerning part in relation to this [offence] is that there were two children in the car," Mr Tonks said.
Walker, of Victoria Street in Bloxwich, was interviewed and charged with a Section 4 public order offence as well as criminal damage to the Ford Fiesta. He pleaded guilty to both charges in a hearing on Monday.
His defence advocate, Mr Brij Chaudhry, said that Walker and his ex-wife had been married for seven years before separating in 2022.
He said Walker had been drinking and was "emotional" at the time of the incident in Bloxwich High Street.
The court had heard that Walker sent text messages to his sister about the victim prior to the attack on the car.
"In interviews he couldn't have been more cooperative, he didn't try to make excuses for his behaviour," Mr Chaudhry told the court.
"He didn't realise the children were in the car when the offences were committed."
It was decided in Monday's hearing that the case would be adjourned so reports can be compiled before Walker is sentenced.
Chair of the magistrates bench, Mr Neil Ravenscroft, commended Walker on the work he has already done on addressing his issues with alcohol.
The case will be heard again on March 13.