10/01/2008 at 08:00 AM EDT
Girls will be girls. And, as Demi Lovato knows, they can be all too cruel.
On Wednesday's The Ellen DeGeneres Show
, the Disney star opens up about the bullying she endured in 7th grade – teasing that eventually prompted her to be home-schooled.
"I never really understood why [I was being bullied] until looking back," she says, noting that she was already a working actress – which made her an easy target. "I had a different lifestyle then everyone else."
Now the Camp Rock
star hopes to use her fame to help other girls.
"I want to help with bullying," she says. "Because there are girls who can't just up and home-school and focus on their career."
DeGeneres was a sympathetic – and outspoken – audience. Bullying is "just so horrible ..." she says. "And somebody has to stop it. It goes on in schools for a lot of different reasons. That's really a shame."
Read more about Demi and other teen sensations!