Aaron Carter calls Hilary Duff the love of his life

Hilary Duff hugs singer Aaron Carter as they attend the premiere of The Lizzie McGuire Movie on April 26, 2003, in Hollywood, California.

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Perhaps the old adage is true: Old flames really do die hard. At least that is for Aaron Carter.

The 26-year-old singer took to Twitter this week to express how he feels about ex-girlfriend Hilary Duff. The couple dated from 2000-2003, and apparently Carter still thinks about her.

He wrote a series of tweets this week about the singer/actress: "Don't be that stupid douche that loses the love of your life forever.. Like me..."

He added, "I'll spend the rest of my life trying to better myself to get back to her. I don't care what ANY of you think."

"That tweet just gave me an anxiety attack," Carter continued before writing, "At least I'm real and don't hide behind the persona of being a celebrity and an entertainer, & try to portray positive feelings all the time."

Duff, 26, and 33-year-old hockey player Mike Comrie, announced they were separating earlier this year. The couple wed in 2010 and welcomed son Luca Cruz in March 2012.

Carter filed for bankruptcy last fall and did a rehab stint in 2011.

During a visit to CBS News in February 2012, Carter -- who's the younger brother of Backstreet Boy Nick Carter -- said, "It's not easy being in the entertainment industry, especially from the time that you're six years old until now. There have been times where it's been very difficult. I got to stay focused, stay on track and continue to embrace what I've been through and not ever forget it -- and be appreciative that I'm here today."

At the time, Carter had been starring in the long-running off-Broadway show, "The Fantastiks." Since then, he has been performing shows and working on a new album.