Simone Back, 42, was pronounced dead in hospital on Boxing Day less than 24 hours after threatening on the social networking website to take an overdose of pills in her flat.
Ms Back, from Brighton in East Sussex, had been left unhappy by long-running problems in her relationship with her girlfriend, according to her friends and family.
Part of a disturbing message she posted on Facebook at 10.53pm on Christmas Day read: "Took all my pills be dead soon so bye bye every one."
A series of messages were then left on the same thread, with some of her online friends expressing concern at whether Ms Back had gone through with her threat.
One poster wrote: "did ya'll catch the part about simone taking a ******** of pills?? .. the 'bye bye' part??
"Did anyone go by personally and check on simone .. or call 9/11?? What's wrong with you people??"
Another wrote: "If any of you lot actually call youself a friend one of you should call around and see if shes ok, so glad I don't personally know any of you, heartless."
Ms Back's death was confirmed by her mother, Jennifer Langridge, on the same thread just after midnight on December 27, stating: "my daughter simone passed away today so plz leave my daughter alone now."
Speaking from her bungalow in Brighton yesterday, disabled 60-year-old Ms Langridge said she believed her daughter could have been helped.
She said: "It is upsetting to think nobody did anything for my daughter. She should never have gone. Normally when she takes overdoses I get help for her.
"I watched my daughter go from a lovely young woman to what she ended up as, someone who didn't smile."
One of Ms Back's friends, Samantha Pia Owen, 48, from Southampton, said: "Somebody could have helped.
"They were all posting how much they care for her but someone should have popped round to see that she was OK."
A Sussex Police spokesman said Ms Back died in the accident and emergency ward at the Royal Sussex County Hospital in Brighton at 5.05pm on Boxing Day.
She said: "Police have investigated and are not treating the death as suspicious.
"The coroner has been informed and a post-mortem will take place in due course."