The actress, became involved in the hit Twilight Saga at the age of 16, and was often ridiculed for not being like every other starlet her age.
"I lit my universe on fire and I watched it burn. Speaking very candidly, it was a really traumatic period in my early 20s that kick-started something in me that was a bit more, feral," the 25-year-old told the magazine. "The public kind of burned me at the stake. But that's OK, I can take it. I'm not dead."
Stewart added, "Between ages 15 and 20, it was really intense. I was constantly anxious. I was kind of a control freak. If I didn't know how something was going to turn out, I would make myself ill, or just be locked up or inhibited in a way that was really debilitating."
But age has come knowledge, and she now says she has finally found peace with the public. "I'm really proud that I am able to move forward and not fall into every mental crater. That's a new thing for me. Age has made me smarter and calmer. And it is [explicit] awesome," she said.
Marie Claire's August issue hits newsstands July 21.
Stewart can be seen starring alongside Jesse Eisenberg in American Ultra, out in theaters August 21.