The 'I Will Always Love You' singer, who had a history of substance abuse, was found dead in the bath tub of her hotel room in February after suffering a heart attack partly brought on by her cocaine abuse, reported Contactmusic.
"Whitney was good at hiding her drug habit. I honestly thought she was clean in the two years before she died. Yes, she would have the occasional drink. And I knew she was taking painkillers and the anxiety drug Xanax. But I never suspected she was using hard drugs.
"It really shocked me when I found that out. And actually it made me quite mad because I thought, 'Whitney, you had us all fooled.' Everyone thought Whitney was in a good place and we never imagined anything like this was going to happen," said Houston's friend and entertainment consultant Raffles Van Exel.