Giti Khairi testified about her relationship with her father, Peer Khairi, who stands accused of stabbing his wife to death in 2008.
The daughter told the court that her father wanted her to follow cultural tradition and marry a cousin, instead of the man to whom she was already engaged.
"He didn't want him to use me and leave me," she testified.
The Crown asked several questions about Giti Khairi's religious beliefs.
The woman — who testified wearing a hijab — said, "I was never a religious person. I never used to wear a hijab."
She testified that all changed after her marriage and just months after her mother Randjida Khairi, 53, was killed.
The mother had her throat slashed and was stabbed five times, in her family's west end apartment.
Peer Khairi, 65, has admitted to inflicting the wounds, but has pleaded not guilty to second-degree murder charges.
The family is originally from Afghanistan. They immigrated to Canada in 2003.
Crown prosecutors allege Randjida Khairi was killed because she stood up to her husband and allowed her children to dress and socialize as they liked.
"I will say that the investigation will reveal it's a situation where someone was frustrated with breakdown of the dynamic of family," said Toronto Police Det.-Sgt. Mike Barsky.
But Khairi's defence lawyer says that's not the case.
"I think as this matter unfolds — I think it's really a sad tale — it's not really a cultural issue, it's not ethnic differences. It's just a sad tale of two people. It has nothing to do with religion or ethnicity," said lawyer Christopher Hicks.
Court was adjourned abruptly after Giti Khairi broke down in tears during her testimony.
The trial will resume on Friday.