A woman accused of murdering Becky Watts "felt sick" at learning her boyfriend had confessed to killing the missing teenager, a court heard.
Shauna Hoare said she was "appalled, disgusted, outrageously angry" at hearing Nathan Matthews had admitted killing his 16-year-old stepsister, dismembering her body in their bath and hiding the remains in a nearby garden shed.
Hoare, 21, also said that boyfriend Matthews, 28, had total control over her life and treated her like a child.
During a series of interviews read to the jury at Bristol Crown Court - where Hoare and Matthews are on trial accused of Becky's murder - she told police of her shock at discovering what her boyfriend had confessed to.
"I'm feeling sick to know she was there, appalled, disgusted, outrageously angry and I feel a bit like I am going to wake up and this is not happening," Hoare said.
"I think it is more angry at the moment than anything - angry he has done it, that he did it, that he could do it when I was there in the house.
"And he acted so normal to me. I am really confused why he did it, what his plans were, how he thought he could get away with it and why.
"I don't understand. I can't even look at him. I just wanted to kill him, bad choice of words. I felt sick looking at him knowing what he did.
"I didn't always like Becky but she was a nice enough girl, she was so young. I don't understand why he did it. I don't understand how he could have done it to us."
Hoare denied any knowledge of Matthews's plan to kidnap Becky, killing her at the teenager's home in Crown Hill, transporting her body in the boot of their car, moving her into their home at Cotton Mill Lane, taking part in the dismemberment and moving Becky's body parts to the shed at 9 Barton Court.
Hoare said during their six years together Matthews controlled her life, including telling her what to eat and supervising her money.
"I feel like a child. He was my dad almost. He controlled every aspect of my life. I don't have any friends any more because of him.
"When I told him I wanted to break up he kind of went psycho and started stabbing himself.
"One way or another it was like I was going to be stuck like this forever. Never be able to go out, do anything.
"I had a dream that one day he would meet someone else, fall in love and leave."
Matthews did not like his Becky but had never spoken about "teaching her a lesson" for the way the teenager treated his stepmother Anjie Galsworthy, his mother, Hoare insisted.
"I didn't ever think it annoyed him to an extreme extent," she said.
"To my knowledge she has never done anything to him or to Anjie or to anyone that to his twisted mind justified him wanting to scare her."
She accused Matthews of being aggressive and said he often took things the wrong way.
"He has been aggressive and violent to me but I never thought he would get annoyed enough or lose his mind enough to do something to do that," she said.
"With the intention to just scare her like that it is so twisted and wrong, I don't understand any of it like his logic, his theory.
"How could he not think that if I found out or if anyone found out he wouldn't be screwed? I couldn't live in a house knowing that he had viciously killed someone.
"You can imagine the suffering she went through, how scared and to imagine I was round there. If I hadn't found the tin we wouldn't have gone over, she would be happily living her life.
"To know that if I had pushed him one day it could have been me. I just don't understand any of it.
"There is still a part of me that does care for him but it is more anger and disgust that he has taken, that he has done that.
"The fact he has no concern for anyone whatsoever. He is sick, physically sick."
Matthews, of Hazelbury Drive, Warmley, South Gloucestershire, denies murder and conspiracy to kidnap.
He admits killing Becky, perverting the course of justice, preventing the burial of a corpse and possessing a prohibited weapon.
Hoare, of Cotton Mill Lane, Bristol, denies murder, conspiracy to kidnap, perverting the course of justice, preventing burial of a corpse and possessing a prohibited weapon.
The residents of the Barton Court property, Karl Demetrius, 30, and his partner Jaydene Parsons, 23, admit assisting an offender.
Donovan Demetrius - Karl's twin brother - of Marsh Lane, Bristol, and James Ireland, 23, of Richmond Villas, Avonmouth - a work colleague of Karl's - deny the charge.
The trial was adjourned.