The threat issued by Jordan Frampton left her fearing she was about to become the victim of violence, city magistrates were told.
Frampton, 26, of Steuart Road, Southampton, also told her: “I am going into the flat. I am taking all my stuff and smash it up.”
The defendant intended her to fear the threat would be carried out, the court heard.
Frampton pleaded guilty to common assault and threatening to damage or destroy property.
He was made the subject of a community order for each offence as well as being told to pay £85 costs and a £114 victim services surcharge.
The two offences occurred on July 13 2024, the court was told.