Whitney Houston's ex-husband Bobby Brown should not be blamed for the singer's personal problems, according to her close friend Bebe Winans.

Gospel star Winans has written a book about his time with Houston, who drowned in the bath tub of her Los Angeles hotel suite last year (12), and he has dedicated a whole chapter to his defence of New Edition singer Brown.

The book is called The Whitney I Knew, and in the chapter titled 'Don't Blame Bobby', Winans comments on the former couple's turbulent marriage, which ended in divorce in 2007.

The singer admits he didn't approve of the relationship, but insists fans are unfair to accuse Brown of causing Houston's personal problems and long-running battle with substance abuse.

In the book, he writes, "Whitney never blamed Bobby for her troubles. Neither should we. I know Bobby. I knew him even before he and Whitney began seeing each other. Like any big brother, I had my concerns about the two of them together.

"You don't want just anyone to take your sister in marriage. You set high, high, high expectations. The bar sits in the stratosphere regarding who you're willing to let through the gate. Several of us close to Whitney felt the same way; this was no secret.

"But it's also unfair and inaccurate for anyone to claim that Bobby ruined Whitney the moment they started hanging out...

"My words here are not meant to diminish Bobby in any way. I simply thought that he and Whitney were unequally yoked. I felt they would be great as friends, but not as husband and wife. Whitney knew I didn't approve of their relationship early on."