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*Bobby Brown has penned a new memoir titled “Every Little Step,” in which he chronicles the good, bad and ugly side of his failed marriage to late music icon Whitney Houston. Brown, 47, talks about the book and opens up about their doomed love story in a new interview with 20/20, confessing that drugs helped lead to their undoing.

“The drugs wasn’t her,” Brown says in a clip from his 20/20 sit-down with Robin Roberts, airing at 10 p.m. on ABC. Revealing that he first saw Whitney taking cocaine shortly before their 1992 wedding. “She did drugs but the drugs didn’t do her. She knew how to handle herself.”

According to her friends and family, who PEOPLE interviewed at the time of her death, there were two Whitneys: the glamorous pop princess groomed by Arista president Clive Davis, and the East coast girl who rebelled against pressures to be perfect by turning to drugs in her early 20s.

“I think not being able to be herself 100 percent was a hell of a burden for her to have to carry. Someone may look good on the outside, sturdy and strong . . . [but] on the inside, you have someone who had insecurities and family issues and emotional personal issues and struggles,” a close family friend tells PEOPLE.

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After Davis signed her to his label in 1985, she “had to do what he said, wear what he said to, sing what he wanted her to sing and act like a goody two shoes when she was really a down and dirty girl from Jersey,” says a record executive who worked with her. “Whitney definitely resented that.”

Adds a music source: “Clive made her into a mainstream pop star and allowed all of her wildest dreams to come true, but being this massive pop star came at a price. She had to act a certain way in front of the cameras for the label. That wasn’t the real Whitney.”

Whitney and Bobby’s explosive, drug fueled marriage ended in 2007, and according to a record executive who worked with the singer for years, Houston “did drugs to escape her pain” from feeling pressured in the music industry and the pain of dealing with her tumultuous relationship with Bobby.

At first, Houston was able to keep her drug use hidden, but “things got worse and worse,” says a family source. “Suddenly, when she was using, she had no idea who she was or who you were and she became angry and lashed out. We’d take turns checking on her in Atlanta when things were bad.”

Surrounded by enablers who “allowed Whitney to do what she wanted to do,” the star was quick to fire someone “if she felt you were not being cooperative on some level,” says the family friend.

Though she entered rehab multiple times, Whitney struggled with addiction until it ultimately took her life. “She was in pain from all the pressure she was facing and the pain from living almost a double life,” says the record executive. “She was doing ridiculous amounts of hard drugs and sacrificed her God-given talents for that.”