Starting her evidence as part of her libel battle against Rebekah Vardy on Friday, the TV personality alleged that private information about her marriage to the former England captain had been leaked to The Sun newspaper.
On September 1 2017, Mr Rooney was arrested for drink-driving as a woman was found in the car at the time.
He later received a two-year driving ban and was ordered to perform 100 hours of unpaid work after pleading guilty to the charge.
On Friday, the High Court was told Mrs Rooney took the couple’s four children and went to stay with her parents following the incident.
She said: “I was in a vulnerable situation, I didn’t know how my marriage was going to work out, whether I was going on with my relationship.”
Mrs Rooney said that the couple later tried to work out their difficulties privately, but did not want the public to know about their potential reconciliation at the time.
In late October 2017 and early November, Mrs Rooney posted two pictures of her children – one on her public Instagram account and a second on her private account – with only the second photo containing Mr Rooney.
Mrs Rooney told the High Court the pictures of the family in matching pyjamas was part of a campaign to support Alder Hey children’s hospital in Liverpool.
She said that despite keeping the photo with Mr Rooney to her “close circle” on her private account, a story was later published in The Sun.
Mrs Rooney said in her witness statement: “Whilst I was comfortable enough to upload the photograph of Wayne to my private Instagram account, I made a conscious decision not to upload the photograph with him in to my Twitter account or to my public Instagram account because of the difficulties between us at the time.”
She later told the court: “That was information that I was happy to share in the private group… but I didn’t want the public to know that.”
However, she claimed that on November 1, the day of the private post including Mr Rooney, an article was published describing the post.
Mrs Rooney said in her written evidence that she was “really hurt” by the leak, “particularly because I felt as though someone that I trusted was betraying me at a very difficult time”.
Mrs Rooney is expected to continue her evidence until Monday afternoon, with Mr Rooney due to step into the witness box on Tuesday.