Megan Fox may be considered one of the sexiest women in Hollywood, but the Jennifer's Body star says she suffers from extreme "self-loathing."

"I'm really insecure about everything. I never think I'm worthy of anything," Fox, 23, tells Rolling Stone in its new issue. "I have a sick feeling about being mocked all the time."

Still, the actress says she lives with that anxiety. "Self-loathing doesn't keep me from being happy. But that doesn't mean I don't struggle. I am very vulnerable."

She can also be "aggressive, hurtful, domineering and selfish, too. I'm emotionally unpredictable," she says. "I've had to say to [boyfriend] Brian [Austin Green], 'You have to go and stop talking to me, because I'm going to kill you. I’m going to stab you with something. Please leave.' "

Fox is vague about other methods she may have used to cope with her feelings. When asked if she's ever cut herself, she tells the magazine, "Yeah, but I don't want to elaborate. I would never call myself a cutter. Girls go through different phases when they’re growing up, when they're miserable and do different things, whether it's an eating disorder or they dabble in cutting."

As for whether the svelte star has an eating disorder, "not that I would talk about," she says.

But one thing Fox is clear about is that when it comes to love and sex, she's a one-man kind of woman. "I can never have sex with someone I don't love, ever, ever, ever. That idea makes me sick. I've never even come close to having a one-night stand. … I'm not sexually promiscuous."

When quizzed about her alleged relationship with Transformers star Shia LaBeouf, she says, "I'm not going to say that I don't love him or vice versa. But it was never on that level."