Johnny McRae, 30, split from the woman in 2018 but she continued to "have problems" with him.
Newcastle Crown Court heard in January 2019 he sent her a message saying she was a "rat" and accused her of having sex with other men.
The following day he was outside her home with a brick and said she was "lucky" to have arrived back before he put her windows out.
He also took her phone and refused to leave when asked.
The day after that he turned up at the house again, caused damage, dragged a sofa outside and hit her head with an air freshener can.
The court heard over a year later, she made the "foolish" decision to visit McRae because he was "upset".
During the visit he assaulted her and she hit her head on the floor after she was thrown onto a coffee table.
McRae, of Belgrave Terrace, South Shields, admitted harassment, theft of a mobile phone, criminal damage, common assault and using violence to secure entry.
Judge Robert Spragg sentenced him to 21 months imprisonment, suspended for two years, with programme requirements, a six month curfew, a ten year restraining order and a £500 compensation order.
The judge told McRae the victim "didn't know what you were capable of doing next".
Judge Spragg said the jail term could be suspended due to the amount of time that has passed since the offences, the fact McRae does not now drink or takedrugs and is working full time.
The judge ordered a progress report from the probation service after two months and warned McRae: "I will be monitoring you".