Carey, 41, struggled to find her words during an appearance on Good Morning America Tuesday.
"I'm almost incapable of talking about this still," the Vision of Love singer said. "It's very heavy emotionally…"
Carey -- who performed the duet When You Believe with Houston -- talked of their friendship.
"It was great, and I don't think people could ever understand our relationship ... There was always this supposed rivalry in the beginning and then we did the duet and we became friends. I saw her toward the end. I loved her. We all loved her… May she rest in peace. "
Carey attended Houston’s funeral at The New Hope Baptist Church in Newark, New Jersey on Saturday, along with a host of other celebs including Kevin Costner, Alicia Keys, Tyler Perry, Stevie Wonder, and Houston’s cousin Dionne Warwick.
"It was gorgeous," Mariah said of the service. "Such a class act. The way she went out and the way family dealt with it, I was very moved."
It was back in 1998 when Houston and Carey teamed up for When You Believe.
Houston died Saturday,February 11 at the age of 48; an official cause of death has yet to be determined.
radar_embed service=5min.com src=" http://pshared.5min.com/Scripts/PlayerSeed.js?sid=1126&width=486&height=412&playList=517713535&sequential=1&shuffle=0"