(digitalspy.co.uk) - Bobby Brown has confessed that he had several affairs during his marriage to Whitney Houston.The couple were together for 15 years before their divorce was finalised last April. Houston now has custody of their 15-year-old daughter Bobbi.In his forthcoming autobiography Bobby Brown: The Truth, the Whole Truth and Nothing But, the R& B singer said the marriage was doomed almost from the start.He wrote: "Within the first year we separated, with several more to follow. I think we got married for all the wrong reasons. Now, I realise Whitney had a different agenda than I did when we got married... I believe her agenda was to clean up her image, while mine was to be loved and have children."He alleged that his former wife felt under pressure to marry and have children after being linked with her female assistant Robin Crawford.Brown, 39, said: "That would kill all speculation, whether it was true or not. In the short, I think I got caught up in the politics and ended up marrying one of the biggest stars in the world."However, he admitted that he had not helped the troubled relationship by being unfaithful, saying: "I am guilty of sleeping with other women... 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 accused Houston of introducing him to hard drugs, insisting that he had never taken cocaine before they met.