Miley attended the Celebration of Life for Janice Freeman Monday at Mariners Church in Irvine ... where she poured her heart out and honored the former 'Voice' singer. You see Miley break down but she still manages to get a laugh when she says, "I was never her coach, ever. She was always mine."

Before surrendering the stage to her dad, Billy Ray, who led a rousing rendition of "Amazing Grace" ... Miley had some touching words for Janice, whom Miley was paired up with during season 13 of "The Voice."

Miley said, "I've learned more from her than anyone that I've ever gotten the honor to be in the room with, not just vocally, I should've gotten more lessons than I did, but she taught me everything that I know about love."

She went on to say, "And, to be here, and I had planned on singing a song for her, but just losing her is just too much for me. So ... my dad's gonna take care of this for me. But, I'll always be your sister, I'm here for you, and I'm here for your family, and Janice I'll miss you more than I could ever say."

Miley joined her dad in song.