A woman charged with murdering her 15-year-old brother, who was accused of using witchcraft, has broken down in court.
Magalie Bamu sobbed as she told the Old Bailey she was forced by her boyfriend, Eric Bikubi, to start hitting her siblings, including her brother Kristy.
Kristy drowned on Christmas Day 2010 during an exorcism, the jury has heard.
Mr Bikubi and Ms Bamu, both 28 from Newham, east London, deny murder.
At the beginning of her defence, Ms Bamu was asked to describe the events in the run up to the death, at which point she cried out: "I don't know how it can come to this point".
The judge told her to take a few minutes to calm down.
She then told the jury how her boyfriend started assaulting her siblings, after he accused them of using witchcraft.
He was punching them and hitting them with a length of wood, the court heard.
Ms Bamu told the jury he then forced her to join in and slap the children.
Asked how she felt she said: "I couldn't do anything I was so scared, I was petrified ...I've never seen Eric like this before".
Mr Bikubi has admitted manslaughter on the grounds of diminished responsibility, which the prosecution has rejected.
Kristy and his siblings were visiting the couple for Christmas.
All three were beaten and other children were forced to join in the attacks, the jury has been told.
But it was Kristy who became the focus of Mr Bikubi's attention, the prosecution said.
Jurors were told Kristy died when he was "too exhausted" to resist and keep his head above water when Mr Bikubi put him in a bath.
Mr Bikubi has admitted assaulting Kristy's siblings.
Ms Bamu also denies two charges of causing actual bodily harm to her other siblings.
The trial continues.