Kate went on to say that she feels differently now after "loads of therapy", and that her character had been her "best friend of 20 years".
"I thought the only thing I’d ever done of value in my life was when I was her. I was lost, and I wondered how I was going to survive without her," she spoke candidly.
"Sally was a great person, a great friend and a great daughter … did people only feel something for me because they liked her?” she said.
Kate first joined the Home and Away cast in 1988 when she was just 10 years old, and after 20 years in the role, she decided to close that chapter.
It's been 13 years since she quit the role of Sally, and Kate said it ended up being the best decision she ever made.
"I think the best thing to come out of all of this, is that I'm great without [Sally]. I nearly choked on the words! We're all great without our security blankets," she said.
Kate has since forged a successful new career in radio, where for the past eight years she's served as one of the biggest stars on Nova FM.
In a new Instagram post however, Kate uploaded the trailer for the interview and wrote in the caption about how her past still lingers with her.
"I worry so often of what people think.. Of me revisiting the same old chapter of my life," she wrote.
She continued: "The chapter people continue to ask me about and the one that defined me. Publicly and personally. One day I’ll move through that worry.. But for now I’ll speak with Anh."