Diddy is publicly speaking about the death of Kim Porter, his on-again, off-again girlfriend of 13 years and the mother of his three children, for the first time.

Porter was found dead in her Los Angeles home Thursday at age 47.

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"For the last three days I've been trying to wake up out of this nightmare. But I haven't," Diddy wrote in an Instagram post Sunday, according to Vibe. "I don't know what I'm going to do without you baby. I miss you so much. Today I'm going to pay tribute to you, I'm going to try and find the words to explain our unexplainable relationship. We were more than best friends, we were more than soulmates. WE WERE SOME OTHER (expletive)!! And I miss you so much. Super Black Love."

Related: Kim Porter, former model, ex-girlfriend of Diddy, dead at 47

The caption was posted along with video from the couple's December 2006 Essence magazine photo shoot. The video showed Porter, who was pregnant at the time with their twin girls Jessie James and D'Lila Star Combs.

Sean 'P. Diddy' Combs (R) and then-girlfriend Kim Porter at the 2006 BET Awards. Diddy mourned the loss of Porter in a recent Instagram post.

Credit: Frederick M. Brown

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Credit: Frederick M. Brown

The music mogul dated the actress and former model off and on for 13 years, ending their relationship for good in 2007. The pair notably remained friendly after their breakup, supporting each other at events and appearing together at family events.

Kim Porter, Christian Casey Combs, Quincy Brown, Sean "Diddy" Combs, D'Lila Star Combs and Jessie James Combs attend 'The Holiday Calendar' Special Screening in Los Angeles in October 2018.

Credit: Charley Gallay

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Credit: Charley Gallay

A cause of death has not yet been announced.