Sean P. Diddy Combs and his then-girlfriend Kim Porter, Picture: AP Photo/Nam Y. Huh

American rap star Sean 'Diddy' Combs has confessed he's been living a "nightmare" since the death of his ex-girlfriend Kim Porter.

The 49-year-old hip-hop mogul dated Kim - who passed away on Thursday - on and off for 13 years, and they also had three children together, Christian, 20, and 11-year-old twins Jessie and D'Lila.

Breaking his silence following Porter's death, Diddy shared a series of emotional tribute posts on social media.

In one video, Diddy can be seen cradling Kim while she was pregnant. He captioned the video: "For the last three days I've been trying to wake up out of this nightmare. But I haven't. 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 S** T!! And I miss you so much. Super Black Love [love heart emoji] (sic)"

View this post on Instagram

#KIMPORTER 🖤🖤🖤🖤🖤

A post shared by Diddy (@diddy) on

Kim was found dead at her Los Angeles home on Thursday after suffering from "flu-like" symptoms for weeks, and the police subsequently confirmed there was "no foul playing" surrounding her passing.