Sean "Diddy" Combs is "devastated and shocked" over the death of his ex-girlfriend and mother of his four children

Sean “Diddy” Combs is heartbroken over the death of Kim Porter, his ex-girlfriend and the mother of four of his children.

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

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

On Thursday, Porter, who was a model and actress, was found dead in her home on Thursday. She was 47.

The Los Angeles County Sheriff’s Office confirmed Porter’s death in a statement explaining that officers responded to a death investigation at 11:40 a.m. in Toluca Lake, California, where they found a female unresponsive at the residence.

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Porter was pronounced dead at the scene.

The cause of death is undetermined at this time. According to an emergency dispatch call posted by TMZ, the call came in as a cardiac arrest. While it’s not yet clear what caused Porter’s death, a source told the outlet she had been suffering from pneumonia for weeks.

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Kim Porter
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Porter and Combs began dating in the ’90s. In 1998, Combs and Porter welcomed their first child together — a son named Christian Casey Combs. Nine years later, Porter gave birth to twin girls, D’Lila Star and Jessie James Combs.

She was also mother to son Quincy Brown, 27, from a previous relationship with music producer Al B. Sure. When Quincy was only 3 years old, Combs was hands-on in raising him.

Porter and Combs called it quits for the first time in 1999 and battled in court over child support for Christian; Combs also dated Jennifer Lopez for two years before he and Porter reconciled in 2003. They split for the final time in 2007.

That same year, Porter revealed to Essence magazine that their relationship turned sour after rumors surfaced that Combs fathered a child with another woman. In 2006, Combs welcomed daughter Chance with Sarah Chapman. Combs is also father to 24-year-old son Justin with ex-girlfriend Misa Hylton-Brim.

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Kim Porter with Sean “Diddy” Combs and their children
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Porter and Combs were able to patch up their relationship and remained close for the sake of their children.

“I’ve been truly blessed to have some great, incredible relationships that have afforded me these children by these very strong, intelligent, beautiful black women,” he says of his exes. “The mothers of my children [are] my best friends. My hat goes off to them,” Combs previously told PEOPLE.

“We’re friends. I’m the person he can tell his innermost thoughts to and he’s that person for me. He still calls me every day and we talk,” Porter also told Essence.