Knox spoke to People magazine recently over several days at her in mother's home in Seattle. The magazine made excerpts of the interview available to The Associated Press.
Last month, Italy's highest criminal court overturned her acquittal in the 2007 slaying of British student Meredith Kercher and ordered a new trial. Italian law cannot compel the 25-year-old Knox to return for the trial, and family spokesman David Marriott has said it's doubtful she will go to Italy.
"When Meredith was murdered and I was arrested, it was so shocking. It was paralyzing. Everything toppled," said Knox, who returned home to Seattle in 2011 after four years in an Italian prison.
Since returning to the United States in 2011, Knox has largely avoided the public spotlight and is mostly left alone in her Pacific Northwest hometown. She tells People she is still dealing with difficult emotions.
"Things creep up on me and all of a sudden I'm overwhelmed by the feeling of helplessness and that desperation and fear to even hope," Knox told the magazine. "Just that can make my heart race and makes me paralyzed until I can breathe it away."
Italian prosecutors have said Knox, who was an exchange student studying in Perugia, Italy, and her then-boyfriend Raffaele Sollecito killed Kercher in a drug-fueled sex assault involving a third man.
They maintained the murder weapon was a large knife taken from Sollecito's house. Prosecutors said the knife matched the wounds on Kercher's body and had traces of Kercher's DNA on the blade and Knox's DNA on the handle.
However, Knox's defenders said she was innocent and was forced to say things she didn't mean during a lengthy police interrogation. And they said bumbling Italian police contaminated the crime scene, producing flawed DNA evidence.
A new trial also has been ordered for Sollecito. An Ivorian man is serving a 16-year sentence for the slaying.
Now studying at the University of Washington, Knox also enjoys rock climbing, hiking, camping and other outdoor activities offered in the Northwest.
Since her return, she has occasionally been seen around town but is largely left alone by the local media.
Knox has a memoir, "Waiting to Be Heard," due out April 30. ABC News reports that Knox has written that she spent most of her time in prison in her cell, which was cold in the winter and hot in the summer, and was only allowed outside one hour a day.
In the memoir, she also details how she eventually became suicidal and thought of swallowing shards of glass or suffocating herself with a garbage bag.
ABC also reported that Knox describes in the book how she wrote her mother a letter just before she was released from prison, anticipating that she might not get out. Knox arrived back in Seattle before her note did.
Knox's full interview will be published in the People's April 26 edition.