In the 911 tape, Haim's mother, Judy, called paramedics from a Los Angeles apartment last week to report her son was not breathing and that he had been feeling ill.
"He all of a sudden got out of bed," a distraught Judy Haim said in the tape. "He wanted to go to the bathroom and he fell on the floor and I put him on the bed and then that was it."
Police have described Haim's death as an apparent prescription drug overdose, but an official cause of death still awaits toxicology results.
Haim's family and friends held a private funeral service for the star in Toronto on Tuesday, where the Canadian actor was born. The Toronto Star reported that about 200 relatives and friends attended, but Feldman was notably absent.
Feldman said in a statement on his website he stayed away to avoid bringing more media attention to the private service.
"I always feared this day would come, and often rehearsed how to face it," Feldman wrote.
"But once confronted with the reality of it, it's so much more painful than I could have ever imagined," he said.
Haim and Feldman starred together three years ago in reality TV series "The Two Coreys".
California Attorney General Jerry Brown has said his office is investigating a prescription drug ring linked to Haim's sudden death.