Mortimer, 40, was released on her own recognizance around 8:30 p.m., just two and a half hours after she was booked into the Palm Beach County Jail on the misdemeanor charge, the sheriff's office says.
According to a police report obtained by PEOPLE, Mortimer was trespassing at the Palm Beach home of Nico Fanjul, son of sugar baron Alex Fanjul. A source tells PEOPLE that Mortimer and Nico Fanjul were dating but had broken up.
Palm Beach County Sheriff
The report states that the reality television star – best known for 2010's High Society – allegedly called authorities asking for a civil standby because she wanted to retrieve belongings from Fanjul's home.
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Authorities allegedly told her that she was trespassing on the property after a previous trespass warning in October and that if she needed assistance, she should come to the police station, the report says.
According to the report, Mortimer allegedly responded by screaming into the phone and hanging up, at which point authorities were dispatched to the house.
When authorities arrived, they allegedly found Mortimer crying and screaming. She said that Fanjul was in the house with another woman, and that she just wanted to get her purse from inside, the report states.
According to the report, Fanjul said that he did not have her purse, and Mortimer was placed under arrest.
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"She sat on his doorstep for hours and banged on the door. She was frantic and very upset. Finally they called the police to get her out of there," the source adds. "She's not a bad person but she was too upset to be thinking rationally."
Another source tells PEOPLE, "I feel sorry for Tinsley."
The second source adds, "She is like the 'poor little rich girl,' always trying to find her way."
The daughter of George Riley Mercer Jr., a real estate investor, Mortimer once had her own line of handbags and clothing, and even appeared on an episode of Gossip Girl. In 2013 she penned a novel called Southern Charm, just a few years after divorcing her husband, socialite, Robert Livingston "Topper" Mortimer, in 2010.
At the time, Mortimer told PEOPLE she was accustomed to "negative press" and enjoyed spending time "at home with my dogs," watching television and searching the Internet.
Mortimer has not commented on the charges against her.
With reporting by AURELIE CORINTHIOS