Nick Carter fears it could take a "lifetime" for him and his family to "fully process" the deaths of his sister Bobbie Jean and brother Aaron.
He made the admission as he paid tribute to his sister Bobbie Jean Carter, 41, who was discovered in the toilet of her home in Tampa, Florida, on December 23 by emergency workers who rushed her to a nearby hospital before declaring her dead.
TMZ reported she was found unresponsive in the bathroom — just like her brother Aaron Carter was at the time of his death aged 34 on November 5, 2022.
Nick said in a new Instagram message about the pain their deaths had caused: "It may take a lifetime to fully process the loss my family has endured over the years — most recently, with the sudden passing of our sister Bobbie Jean. I am completely heartbroken. Thank you for all your love and kind words".
"We are reminded again that life is precious, fleeting and to cherish the time we have with the ones we love. I know she is finally at peace with God. I love you BJ."
Nick added a throwback image of him and Bobbie playing outside as children alongside his Instagram message.
Bobbie Jean and Aaron are the second and third of the Carter siblings, respectively, to die at an early age.
Their sister Leslie Carter died in 2012 at the age of 25 of a prescription medication overdose.
Some of the I Want Candy singer Bobbie's ashes were spread with Leslie's in the Florida Keys following his death.
Nick and Aaron's twin, Angel, are the only remaining Carter siblings alive.
In June, Bobbie was arrested for retail theft and drug possession after allegedly trying to steal $55 of crafts from a Brooksville, Florida, Hobby Lobby.
But her roommates informed authorities Bobbie had stayed away from drugs since her release from prison.