The reality star has been warned she is "at risk of going to prison" after admitting to the offence.
The former glamour model is accused of sending her ex-husband, Kieran Hayler, an abusive message about his fiancee, Michelle Penticost.
The reality star is due to appear in court next month.
The former glamour model has changed her plea, after previously claiming she was "definitely" not guilty of the charges.
She has agreed a plan to pay back her debts.
Katie is divorcing her husband of four years after he admitted to another affair.
'Onwards and upwards.'
'I do worry what tomorrow brings.'
'I hate myself for what I've done to her.'
She spoke to her fellow 'Loose Women' about her break-up.