When Charlize Theron decided to start a family on her own back in 2012, the fact she was a single parent wasn't the reason she chose to adopt.

The actress' decision harkens back to a letter she wrote as an 8-years-old. It read: "What I want for Christmas this year is for [mom] to take me to the orphanage so that we can adopt a brother or a sister."

The South African beauty admits she doesn't know where the desire to adopt first came from. "Maybe it was just an awareness of the fact that at that time, orphanages were everywhere in South Africa," she muses.

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Theron with 2-year-old son Jackson

And it wasn't until her and ex-boyfriend Stuart Townsend contemplated starting a family that she realized her desire to adopt was stronger than her desire for biological children.

"[Stuart and I] had very different ideas of what a family looked like," Charlize says of her ex. "There's no judgment; that was not the reason why we broke up, but when we did, adopting was not a last resort for me — it was almost like a first resort."

In March 2012, Charlize adopted her now two-year-old son Jackson and says it's easily the best decision she's ever made.

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"[Adoption is] the only thing in my life that's surpassed how great I thought it would be," the pixie-haired star gushes.

But life wasn't always so blissful for the Oscar winner. Charlize admits to hitting "rock bottom" in her early 30s after suppressing emotions related to a trauma experienced in adolescence.

The 38-year-old "didn't know" she needed therapy following the murder of her father by Charlize's mother when she was 15. Her mother faced no charges after acting in self-defense.

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Theron with mom Gerda at this year's Academy Awards

"I was walking through life just kind of thinking everything was fine," shares the actress. "You go and you work and there's this catharsis that happens when you are an actor, and that's healthy, right?"

Charlize claims regular therapy sessions is what ultimately saved her.

"I called a friend and said, 'Will you give me the number of your therapist?'" she tells Vogue magazine in the new issue. "And I started seeing an incredible woman who is always just a phone call away."