Ashlee Simpson: I Feel Credible With Myself

Or something like that.

Some success in her various professional roles, and her romance with her "best friend" and Fall Out Boy bassist Pete Wentz, has Ashlee Simpson sounding downright giddy about life these days. And she's a lot more resilient than she used to be.

Chief among Ashlee's confidence-boosting achievements of late, she tells CosmoGirl - her 2006 stint as Roxie Hart in the London production of the musical Chicago.

"There was a time when what people said about me could really get to me. But working on Chicago helped me come into my own," says Ashlee Simpson.

"[Theater acting] had been a dream of mine since I was little. It taught me to be more comfortable with myself."

That level of self-possession, the 23-year-old lip-synching queen and daughter of Joe Simpson admits, helped her deal with fame significantly better, too.

"I've gotten to a point where being credible with myself is more important to me than what anyone else says," she explains. "People make up stories about you, but they don't really know you. ... I'm not fazed by that."

Simpson also credits Pete Wentz, 28, with providing encouragement in her private life that has boosted her professional work - in particular, her third album, which is due out next year and which should be awesome.

"He's a great sounding board and very supportive," Simpson says. "Pete and I compliment each other. We are best friends, and we encourage each other. I think that is so important. It builds a solid foundation."

She did not talk about the Pete Wentz sex tape rumors at all.