Mariah Carey's estranged sister, Alison, hoped she could still repair her fractured relationship with her mega star younger sibling as she wasted away on her deathbed.

Alison's friend and healthcare proxy, David Baker, told DailyMail.com family members knew Alison had been in hospice care for the past month at her apartment in the small town of Coxsackie, New York - just 24 miles south of Albany.

The 'Vision of Love' singer, however, never called to check on her dying sister, Baker said. 

'Alison was hurt by the way she was treated by her mother and Mariah, but she always had mixed feelings about her mother,' Baker told DailyMail.com exclusively. 'But I know it was her dying wish if she could've at least had a conversation with Mariah.'

On Monday, Mariah confirmed that her mother, Patricia, and Alison passed away.

'My heart is broken that I've lost my mother this past weekend,' Mariah said in a statement to People. 'Sadly, in a tragic turn of events, my sister lost her life on the same day.'

She continued: 'I feel blessed that I was able to spend the last week with my mom before she passed. I appreciate everyone’s love and support and respect for my privacy during this impossible time.'

Baker confirmed Mariah never called Alison while she was in hospice, but Alison's four adult children visited her at her apartment in Coxsackie within the past month.

Mariah had been upfront about her estrangement from her older sister, who had battled drug addiction for years.

In her 2020 memoir, The Meaning of Mariah Carey, the singer called Alison her 'ex-sister' and claimed Alison tried to get her to use drugs and had 'inflicted [her] with third-degree burns' when she was a pre-teen.

'When I was 12 years old, my sister drugged me with Valium, offered me a pinky nail full of cocaine ... and tried to sell me out to a pimp,' Mariah wrote in her memoir. 'Something in me was arrested by all that trauma. That is why I often say, "I'm eternally 12." I am still struggling through that time.'

Mariah said she finally made the decision to cut Alison out of her life in order to not be 'an enabler'.

The estrangement was extremely painful for Alison, Baker said.

'It stung because Mariah called Alison her ex-sister,'  Alison's pal told DailyMail.com. 'She used to babysit and take care of Mariah. When that came out, she couldn't believe that Mariah had done that because she already was not talking to her, but then she kicks Alison in the teeth while she was already down.'

Alison was a recovering drug addict and had worked as a prostitute in New York to make ends meet. In 1990, she was diagnosed with HIV, although Baker questions whether that diagnosis was accurate.

Alison continued to spiral and was arrested in 2016 in Saugerties, New York for alleged prostitution.

On Tuesday, Baker confirmed to DailyMail.com that Alison did not die from cancer or HIV. He would not divulge the exact cause of death but said Alison passed away early Saturday morning due to 'internal organ failure'. 

Baker said he found Alison unresponsive at about midnight on Saturday. A nurse was called, who confirmed the 63-year old had passed away. 

'She was on medications to make her feel comfortable and there was no indication that she was distressed or in pain,' Baker said. 

The pal said Alison's four children visited her a few weeks before she passed.

In a heartbreaking 2016 interview with DailyMail.com, Alison made an impassioned plea to her famous sibling and begged her for financial support as she battled back to health setbacks following a devastating home invasion attack in 2015 that left her brain damaged. 

Since that attack, Alison had been in and out of the hospital.

'Mariah I love you, I desperately need your help,' she said to Mariah in the 2016 interview. 'Please don't abandon me like this.'

Baker, who had been Alison's healthcare advocate and proxy for the past nine years, said the 63-year old has been sober for more than three years but her health continued to decline. 

Before getting her apartment in a tiny town in upstate New York, Alison was staying at a facility where she was undergoing physical rehabilitation. 

Alison often wondered if her famous sibling would ever reach out to her as she clung to the last weeks of her life. Baker said his friend of nine years was barely conscious during the last two weeks or so before she passed away on Saturday.

Baker blasted the songstress and the prepared statement that was released following the two women's deaths.

'It was awful because it was just all about her,' Baker said. 'In her eyes, it's all about Mariah and never anyone else. 

'If she would've cared about her, she would've talked to Alison when she knew she was dying. It's how Mariah has been for a very long time. She will do anything to get attention and is always looking for publicity.'

Mariah also was estranged from her opera singer mother at one point. 

The 'Honey' singer wrote in her memoir that her mother's jealousy over her successful career may have caused a lot of the friction in their relationship.

'[That jealousy] comes with the territory of success, but when the person is your mother, and the jealousy is revealed at such a tender age, it's particularly painful,' she wrote of Patricia.

Carey’s mother was reportedly living at a senior care facility in West Palm Beach after Mariah sold her mother's Westchester County, N.Y., home, which she had bought for her in the 1990s.

Although they had a difficult relationship, Mariah and Juliard-trained opera singer Patricia appeared in Christmas specials with her famous daughter.

Meanwhile, Mariah stayed estranged from her siblings.

Both Alison and Mariah's older brother Morgan, 64, previously took legal action against their little sister for what they claimed were 'cruel and outrageous allegations' made in her book.

In a March 2016 interview with DailyMail.com, Morgan said Alison inherited $1.6million from her father Alfred Carey, when he died in 2002. 

A trust fun had been set for Alison's children but Alison continued to struggle with mounting medical bills.

The rest of the money she has squandered on her drug addiction, Morgan said.

Baker said Alison was honest about her struggles but still hoped she would someday make amends with her family, especially Mariah.

'[Alison] was a very intelligent and very sensitive person who had a really rough time in her life,' Baker said. 'She had a lot of obstacles in her life starting from when she was very young, and I don't think most people could go through something like that and not be affected.

'[Mariah] called her an ex-sister, which was a nasty thing to say and [Alison] never got over that. She continued to dismiss her, as if there was something she could do to change that. No mater what, she will always be her sister.'