Nick Carter is mourning the loss of his sister, Bobbie Jean Carter, who died on Dec. 23 at the age of 41.

On Thursday, the Backstreet Boys singer, 43, shared a childhood photo and an emotional statement to Instagram about Bobbie Jean's death, which came a year after their sibling Aaron Carter died in November 2022 at the age of 34. Nick's sister, Leslie Carter, died at 25 in January 2012.

"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," Carter wrote. "I am completely heartbroken."

He went on to share his gratitude to fans for the support he's received. "Thank you for all your love and kind words," he said. "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," the message ended.

Multiple sources confirmed to PEOPLE that Bobbie Jean, the sister to both Nick and Aaron Carter, died. Sources close to the family said that the Carters believe she went into cardiac arrest, as further details regarding her death remain unclear.

TMZ first broke the news, reporting that Bobbie Jean died in Florida, citing her mother, Jane Carter. "I am in shock from learning of the sudden death of my daughter, Bobbie Jean, and I will need time to process the terrible reality of this happening for the third time," she told the outlet.

"When I am able to think clearly, I’ll release a fuller statement, but until then, I would request to be left to grieve in private," Jane continued. "[H]owever deeply a parent feels the loss of a child, the suffering of a young child at the loss of a parent must be much greater. So, I would ask the sympathetic to say a prayer for my precious 8-year-old granddaughter Bella, who previously lost her father and is now also left without her mother."

Several days after it was confirmed that Bobbie Jean had died, a Carter family source told PEOPLE that her only daughter Bella, 8, is currently in the care of an aunt on her father's side.

In addition to working alongside her brothers Nick and Aaron during their respective music careers, Bobbie Jean also appeared on eight episodes of the family's E! reality television series, House of Carters, in 2006, per IMDB.

Last June, she was arrested in Florida after allegedly stealing stickers and markers from a Hobby Lobby store and was later reportedly found to have drugs on her person.

Back in November, Nick opened up to E! News about his grief surrounding Aaron's death and how he still had a difficult time accepting the loss a year later. "It's still unbelievable to me," he said. "I'm still processing the whole situation and trying to make sense of it — because it hasn't. But I'm hoping that one day I can make sense of it all."

Since Bobbie Jean's death, Nick has been sharing sweet moments with his kids on his Instagram. On Sunday, the father of three posted a short video of his son Odin Reign, 7½, golfing. Then, on Tuesday, the musician — who also shares daughters Pearl, 2½, and Saoirse Reign, 4, with wife Lauren Kitt Carter — uploaded a clip of Saoirse playing piano.

"Cherishing these moments," he wrote.