"I lit my universe on fire and I watched it burn," she told Marie Claire for its August cover.
She continued, "it was a really traumatic period in my early 20s that kick-started something in me that was a bit more feral. ... 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."
Stewart added that after a very public split from Pattinson and a scandal with her "Snow White and the Huntsman" director, she was finally able to deal with her celebrity and fame.
"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 f****** awesome," she said.
In fact, her new liberating persona also came with a new look and a shorter do.
"My hair was such a crutch. I looked quote unquote 'sexy' no matter what," she said. "I could hide behind it. As soon as I didn't have all that hair, I had to let my face hang out. I felt more confident than I had in a really long time. And it felt really good. Maybe to most people long hair is prettier. But then what?"