The mom of Backstreet Boys' A J McLean will talk Friday on ABC's 20/20 about the setbacks that led the band's bad boy into rehab for alcohol and depression.

Denise McLean tells Connie Chung that she sees AJ and the sweet son she calls Alex as two different people in the same body. Alex's grandmother helped rear him, and when she recently died, Denise says he didn't have coping mechanisms to deal with the loss. And when the father he'd never really known re-entered his life, ''He quickly began to realize and be very hurt by the fact that his father wasn't interested in him because of him being his son. He was interested because he was a Backstreet Boy.''

Denise says AJ is the one who ''makes all these pelvic thrusts and does all this stuff to drive the girls crazy. And AJ is the one that got the tattoos, and ..'s the one that colors his hair. Alex is the complete opposite, the sweetest, most gentle person you could ever imagine. He's kind, he's got a heart of gold, he loves his family, he loves his puppies to death.''

But his mom says Alex just ''got smothered by A. He just got lost in the hype, the drinking, the lifestyle, the fame.''

Denise tells Chung that entering detox was the right decision for AJ, who has been out of residential treatment for almost two weeks. ''He called me two days after he was in, and I was absolutely amazed at the calmness in his voice. You could hear in his voice that he felt safe. He was where he needed to be.''

Though she says he looks and feels strong, they know it's probably too soon to go back on stage. ''He's secure in his voice, he's secure in his dance steps, he's secure in every move he makes. When he's offstage, Alex is one of the most insecure people I know. And he's going to have to deal with that now. As well as the alcoholism.