Kate Moss felt she had to testify at he ex Johnny Depp’s defamation trial.

The 48-year-old supermodel made headlines in May when she appeared virtually during Depp’s trial against ex-wife Amber Heard, and speaking with BBC radio, she explained why she testified.

READ MORE: Kate Moss Testifies For Johnny Depp In Trial, Undercuts Amber Heard’s Version Of Stairs Incident

“I believe in the truth and I believe in fairness and justice,” she said.

In her testimony, Moss disputed a claim that when they dated in the ’90s, Depp had pushed her down a flight of stairs.

“I know the truth about Johnny,” Moss said. “I know he never kicked me down the stairs. I had to say that truth.”

Last month, a jury decided that Heard had defamed Depp in an op-ed where she said she was a victim of domestic violence, awarding the actor $10 million in damages.

READ MORE: Kate Moss Attends London Show To Watch Johnny Depp Rock Out On Stage

In her BBC interview, Moss also opened up the backlash she received after photos were published of her doing cocaine in 2005.

“I felt sick and was quite angry,” she said, “because everybody I knew took drugs. So for them to focus on me, and to try to take my daughter away, I thought was really hypocritical.”

Moss wasn’t charged, but she lost a number of lucrative brand contracts and was forced to make a public apology.

“I had to apologise really, if people were looking up to me,” she said, looking back.