Less than a week afterSean “Diddy” Combs‘ former romantic partner —and mother of four of his children—Kim Porter was found deadin her home, the 49-year-old hip hop mogul is reeling from the sudden loss.

“This is the most awful, sad and unreal situation for him. It’s a nightmare,” a source close to Combs tells PEOPLE. “He is very much struggling. He isn’t sleeping. He always had a very special relationship with Kim. Despite not being together romantically, he loved Kim. It was really true love and he is hurting badly right now.”

Insiders tell PEOPLE that Diddy held a memorial for his former girlfriend at his Bel-Air home on Sunday afternoon. Among the 100 guests present werePharrell Williams,Mary J. Blige,French MontanaandKourtney Kardashian.

Kim Porter and Sean “Diddy” Combs.Chris Polk/FilmMagic

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“He is very involved in making arrangements for Kim. He wants it all to be very special,” the insider continues.

Diddy showed a glimpse of the candle-lit memorial on his Instagram Story on Sunday.

“It was a beautiful memorial for Kim,” the source tells PEOPLE. “Diddy is still beside himself. He was very emotional, but grateful how many of his friends showed up to honor Kim.”

Sean Combs Instagram; John Shearer/Getty Images

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Diddy again paid tribute to his late love on Monday,sharing a video of Porter dancing. “She loved to dance,” he captioned his Tweet. “Thank you to everybody for your prayers and support. God is the greatest. He woke you up to see another day. Please don’t take it for granted. Let’s go people!!!”

The Los Angeles County Sheriff’s Office confirmed Porter’s deathin a statement. Officers were alerted after a woman was found unresponsive in Toluca Lake, California. She was declared dead at 11:40 a.m. local time on Thursday.

“Diddy is devastated and shocked,” a source previouslytold PEOPLE. “He and Kim were still very close friends and co-parents even though their romantic relationship didn’t work.”

“They were still a family,” the source continued.

source: people.com