Bobby Brown

R&B singer Bobby Brown has confirmed he was unfaithful to his former wife Whitney Houston, admitting shocking details of the couple's relationship in his autobiography 'Bobby Brown: The Truth, the Whole Truth and Nothing But', due out next month. He writes: "I never used cocaine until after I met Whitney. Before then, I had experimented with other drugs, but marijuana was my drug of choice. At one point in my life, I used drugs uncontrollably. I was using everything I could get my hands on, from cocaine to heroin, weed and cooked cocaine." The couple's marriage was officially dissolved last year but Brown fought to overturn the ruling in a bid to gain custody of their 15-year-old daughter Bobbi Christina and win spousal support. A judge dismissed his claims earlier this year after he failed to show up to a court hearing. But now, Brown has admitted their marriage was in trouble for a long time and he jeopardized their relationship by cheating on his wife on numerous occasions. "I am guilty of sleeping with other women,” says Brown. “Women are always throwing themselves at you. I'm only human, so I would make the mistake and bite the hook sometimes. I let the testosterone take over." Brown also describes his 14-year marriage as "doomed from the very beginning." "I think we got married for all the wrong reasons," he says in the book. "Now, I realize Whitney had a different agenda than I did when we got married ... I believe her agenda was to clean up her image." Whitney's rep responded in a statement to PEOPLE: "Miss Houston is sad that Bobby feels he need to say such things but she chooses to take the high road and will not speak badly about the father of her child even if it's to set the record straight."