The singer spoke candidly about his grief following the iconic star's passing, and noted his feeling of "emptiness".
"Over the past few days I've tried to process the emptiness that I am experiencing. What my heart feels cannot be expressed in words," he said.
"Nippy, I miss you so much! You were so happy and full of love. Your smile will live in my heart forever."
The 31-year-old singer, who was a close friend of Houston's, will be among the guests at her funeral on Saturday (February 18).
Other guests in attendance will include Brandy, Clive Davis, Alicia Keys, Kevin Costner, and Aretha Franklin. The funeral will be streamed live on TV and the internet.
Houston was found dead last week, just hours before she was scheduled to perform at mentor Davis's annual Grammys pre-party.
Ray J allegedly tried to enter Houston's room at the Beverly Hilton hotel that night, but was turned away by LA police.
Houston and Ray J were rumoured to be dating at the time of her death, but Ray J maintains that they were just friends.
Watch Whitney Houston sing 'One Moment in Time' below: