Pop singer Britney Spears says she "truly hit rock bottom" during a stint in rehabilitation this year but told fans she did not blame her behavior on alcohol or depression."I was like a bad kid running around with ADD (Attention Deficit Disorder)," she wrote on her Web site, "I confess, I was so lost.""I think the whole problem was letting too many people into my life," the 25-year-old singer said. "You never know another person's intentions or what another person wants."Earlier this year, Spears split from her second husband, aspiring rapper Kevin Federline, with whom she has two children. She entered rehab after a spree of high-profile partying and erratic behavior such as shaving off her hair.Spears told fans about having to "cut so many people out of my life" after learning that some were taking advantage of her vulnerability and her wealth."Some of the people in my life made more of some issues than was necessary," she said, citing as an example of her hitting the party scene after her divorce."I think it is actually normal for a young girl to go out after a huge divorce. I think it was a bigger issue because I had not gone out in such a long time," said Spears, who has not released an album since 2003. After leaving rehab in March, which she described as a "humbling" experience, Spears completed a divorce agreement with Federline and fired her manager Larry Rudolph. Spears said she is now dealing with insecurities from her childhood. She is trying to stage a comeback, performing for the first time in more than three years this month with a series of 15-minute shows at various nightclubs and reportedly working on her fifth album. Spears said she hoped her new letter would make people "think a little bit more of me and where I am coming from," adding that she tries to make herself numb to stories written about her rather than getting angry."I do see the world with a completely different set of eyes now," Spears said. "I do still have a lot to learn, and I am going to make mistakes everyday, and I am sure every mistake I make will probably be on CNN or Good Morning America."