O’Neill said she feels ‘sickened’ that she continued to date Bayley for months afterwards but he "got into my mind."
"I don’t know why I didn’t leave him at that point," she said.
"I wanted to see him and I knew it was wrong but he manipulated me I guess. I felt like I really loved Adrian. He really had a hold on me.
"He dressed so well, talked with manners and he always had his hair in a smart style. I had no idea of what he had really been in prison for, I feel sick."
Meanwhile, Bayley's former best friend, 27-year-old Dan Spana, has labeled him a "monster" who deserves to "suffer in prison."
"A death sentence is too easy for him. I want him to suffer with life in prison for what he did to that poor woman.
"If anyone met Adrian before they knew this, what he had done – they would have thought him a nice guy. He really deceived everyone,’ said Mr Spana.
"He is evil – sick in the head. He was so strong. He liked to fight in the ring and keeping fit and strength was a high priority to him. He didn’t mind having a fight, he enjoyed it. How could that poor woman have ever stood a chance?
"It’s sick. I don’t know how someone could do that to a woman. He was so kind to me and I never even had the slightest clue what he was capable of."