R&B star Ray J has spoken of his heartache following his on/off girlfriend Whitney Houston's sudden death, insisting his pain "cannot be expressed in words".

Ray J began dating the I Will Always Love You legend in 2007 after her divorce from husband Bobby Brown, but the couple split in 2009.

The two were briefly linked in 2010, and they were said to have reunited once again earlier this month after Houston and Ray J were snapped leaving a restaurant together in Los Angeles on 4 February.

The icon was found dead in her Los Angeles hotel room exactly one week later and now Ray J has broken his silence to TMZ.com to express his sorrow over the devastating loss of his longtime love.

Affectionately referring to Houston by her nickname Nippy, he says, "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. The world lost an icon, but I lost my close friend. Nippy, I miss you so much! You were so happy and full of love. Your smile will live in my heart forever."

Houston will be remembered by friends and family during a star-studded memorial service on Saturday in her native New Jersey, and a representative for Ray J confirms the 31 year old will be in attendance to pay his respects.

Ray J's singer sister Brandy recently issued her own statement following Houston's passing, saying, "My heart is destroyed. I lost my idol and dear friend. My prayers go out to Whitney's family and her millions of fans around the world. Whitney - the greatest voice of all time - you are my angel and I will always and forever love you."