Former NYPD Blue star Kim Delaney is heartbroken over the sudden death of her brother, and friends fear the latest blow could drive the 43-year-old actress to drink — again.

Kim was at a family get-together in Vetner, New Jersey, on July 17 when her brother John, 47, collapsed during a game of basketball. A family source said: “Everyone was having a good time laughing and teasing each other when all of a sudden John collapsed.”

Initially everyone thought he had just passed out from heat exhaustion, but when they could not get him to respond they called an ambulance. Medics failed to revive John, father of 14-year-old twins. He had suffered a heart attack.

“Kim, who’s close with her entire family, was closer to John than anyone and is taking his death very hard but is trying to keep it together for his kids,” the source added.

Former teen model Kim got her start in acting on All My Children in the early ’80s. She went on to do a string of straight-to-video movies and then won an Emmy as Jimmy Smits‘ detective girlfriend Diane Russell in NYPD Blue‘s ’90s heyday.

In 2003, Kim entered an Arizona rehab clinic for alcohol addiction. A friend said: “Kim doesn’t look good and we’re all very concerned this will send her so far over the edge we won’t be able to get her back.”