Dove Cameron is opening up about the "very disturbing" death of her childhood best friend.

On the February 4 episode of Call Her Daddy, the "Boyfriend" singer, 30, spoke to host Alex Cooper about the death of her friend Hayley, who was murdered by her father at 9 years old along with her sister Kelsey, per People. She recalled how they met when they were 2 years old and instantly formed a connection that held true until she passed away.

"I had stayed with her dad for quite a lot of the summer before [the murder] happened," she said, noting that her friend's parents went through a "messy" divorce. "And I think even at 8, it was like a dark energy. He was a very angry man."

Cameron recalled inadvertently learning of her friend's tragic death when she was home sick from school one day by listening into a phone call between her parents and her friend's preschool principal.

"She basically said like, 'This is going to be a really, really disturbing call. Haley and Kelsey are gone. Steve is gone, and he took the girls with him,'" she recalled. "They heard me like express some sort of child noise, like a gasp. And then they came in and we just didn't get out of bed for two days."

The Descendants alum said her parents put her in therapy to work through the situation because "it was so impossible to process," especially with how much time she spent around the family.

"I was very very very very very disturbed by knowing someone for all that time and being raised around them and then realizing that they are capable of doing something so harrowing," she said, admitting that it "fissured" her brain and impacts how she processes things to this day. "I still have issues."

Cameron explained that she "rarely" talks about the traumatic experience, "not because it's a problem to talk about but [because] it's so not the first thing that people usually ask me."

If you or someone you know is struggling with mental health problems, emotional distress or suicidal thoughts, there is help. Contact the 988 Suicide and Crisis Lifeline 24/7 by dialing "988," visit the website at 988lifeline.org or reach out to the Crisis Text Line by texting "HOME" to 741741.