Farrah Abraham says fellow Teen Mom star Catelynn Lowell has a "weight problem" and is jealous of her fame Credit: Todd Oren/WireImage.com

It's lonely at the top -- or wherever it is Farrah Abraham finds herself these days. After selling her XXX-rated "home video" with porn star James Deen for a nearly $1 million payday, the 21-year-old Teen Mom alum is out to prove that she's not the sexed-up schemer some have made her out to be.

Us Weekly caught up with the single mother (to daughter Sophia, 4) on May 7, one day after the release of Farrah Superstar: Backdoor Teen Mom on porn company Vivid's website. (According to TMZ, the racy flick attracted more than 2 million visitors in its first 12 hours online.) During the revealing chat, Abraham defended her actions to Us' Brody Brown and talked about how she's dealing in the wake of the scandal.

Though she said before that she got "great feedback" from the porn companies that wanted to buy her sex tape, not everyone is a fan. Fellow Teen Mom Catelynn Lowell, for example, tweeted that her former costar sounded like a "dying horse" on the video. But Abraham seems unfazed by the criticism.

"I know what jealousy looks like," she told Us of Lowell's tweet. "I am trying to be a role model for the other Teen Moms. I try not to knock them down. I try to better them."

Then, addressing Lowell specifically, she added: "Catelynn has a weight issue, but I don't say harsh things about her to hurt her self-esteem."

Abraham also opened up to Us about accusations that she's a "slut" and her plans to "change the world." For more from the interview -- including details on her quest for love, her thoughts on Deen, and what she's going to tell her daughter about the XXX-rated tape -- pick up the new issue of Us Weekly, on stands Friday.