“Very sadly, we have been informed that my sister Annabelle, died as a result of a heart attack at home last Thursday,” sister Camila Neilson says in a statement obtained by PEOPLE. “It has come as a complete shock, as she had many plans having recently returned from Spain.”
“My parents and I are devastated and shocked by this news,” continues the statement. “We would ask the media to respect the privacy of our family and Annabelle’s close friends during this very difficult time. We will not be making any further statement at this time. We thank you for your consideration.”
PEOPLE confirmed the Bravo personality and British aristocrat’s death on Monday. She was 49.
Authorities told PEOPLE on Tuesday that they are not treating Neilson’s death as “suspicious,” with U.K. police issuing the following statement in regards to the Ladies of London star’s passing: “Police were called by the London Ambulance Service at approximately 22:20 hours on Thursday, 12 July, to a residential address … after a woman had been found deceased at the location. The death is not being treated as suspicious by police.”
The coroner’s office told PEOPLE they have yet to open an inquest. PEOPLE has reached out to the coroner’s court for more information.
A source told PEOPLE that Neilson’s “friends and family are stunned.”
The source also said Neilson endured plenty of “hard times” in her life, most notably the 2010 suicide of her best friend, designer Alexander McQueen — “she was rocked by his death” — and a horse riding accident five years ago that left her in agony. (“Coping with the pain was horrific,” said the source.)
Ultimately, the source said Neilson “had a lot of private pain that she kept from others.”
Neilson also previously struggled with a heroin addiction. She told the Daily Mail in 2015 that her addiction began when she was attacked by a man at the age of 16, “tied to a tree and continually beaten.”
“I managed to escape with my life but I needed reconstructive surgery because my face was so disfigured,” she said. “After that, I fell into a serious depression and became a heroin addict because it provided an escape bubble and was the only way I could cope.”