The Oscar-nominated star spent a significant portion of her education in the healthcare system.
The 43-year-old previously revealed she was charged with attempted murder when she was 14.
She was sentenced after threatening to kill an older girl with a knife that harassed her in the care home.
Recalling the incident during an appearance on the BBC’s Desert Island Discs, she said she attended a rave, took drugs and came home to find out that a nine-year-old boy had been “taken away”.
The BAFTA and Golden Globe winner said she ‘broke’ – suspecting the girl was guilty.
She said, “I broke down and said I was going to kill her. I didn’t hurt her, I didn’t touch her, but I said these words. And I regret it and I’m sorry and I was sorry. ”
The mother-of-three, whose roles include Oscar-nominated Woody Allen’s comedy Sweet and Lowdown and 2003 drama America, said she spent three days in solitary confinement – in an adult cell.
“I was mortified,” she says.
She added, “And I’m sorry for her. We have all been mistreated. She was a child herself. No one looked after us properly. We riot in this house because they locked the refrigerators at night.
“We were not safe. ”
Morton also said, “I’m incredibly sorry. But it wasn’t just self-defense. I was angry with the system. She said she wanted to “clear things up a bit.”
Morton said her strong faith in God had helped her through the trying times in her life.
She said, “When I was little I was very confused with my relationship with faith, but I always felt loved.
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“And the same way I look at my kids and I know I love them, and it’s so huge and it’s so overwhelming and it’s so huge, it’s the love I feel from God.” ”
Morton continued, “And so when you’re little or in pain or in a very, very difficult situation, by accepting that love and allowing that love, the most amazing and transformative things can happen to you. .
“That’s how I think I was able to survive, I guess.