Kathryn Isobel Hay, 49, won the national pageant crown in 1999 and was also Miss Tasmania in the same year.
She served four years in the island state's parliament from 2002 as a Labor member in the electorate of Bass.
Hay had pleaded not guilty to one count of emotionally abusing or intimidating then-partner Troy Shane Richardson from 2014 to 2022.
She was found guilty in Launceston Magistrates Court on Wednesday, with the majority of the particulars on the charge proven.
Mr Richardson told the hearing in 2024 Hay was verbally abusive, punched him, threatened him with violence weekly and hit him multiple times with a shoe.
Mr Richardson said the pair met in 2009 at a dog show and married in 2012.
He told the court their relationship was "all rosy" but things deteriorated around 2013 after the birth of their second child.
On a return trip to Tasmania, Mr Richardson said Hay threw a bowl of cereal at him and called him useless, pathetic and a c***.
"She would often make a point of having an argument in public just to make me feel low," he said.
Mr Richardson said he was left with a black eye after Hay punched him in 2020.
In 2021, Hay was taken into police custody for allegedly slapping Mr Richardson for driving around a corner too fast leading to a family violence order against her.
Mr Richardson said Hay later demanded he have the order revoked and spent 79 minutes on the phone with him telling him what to write.
Hay denied being physically abusive but admitted on occasion using bad language as the relationship became toxic.
She told the court it was possible Mr Richardson sent messages to himself because he had access to her passwords and Facebook account.
Hay also accused Mr Richardson of being financially controlling, something he denied.
Hay's bail was continued. She is expected to be sentenced on April 17.
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