Angel Carter "begged" her twin brother Aaron to let his family "help him" two days before his tragic passing.

The 'I Want Candy' hitmaker was found dead in his bathtub in November, and on the pair's 35th birthday on Wednesday (07.12.22), Angel opened up about facing "unimaginable loss" because of "untreated mental illness and the addiction that it led to."

Their sister Leslie died of an overdose aged 25 in 2012, after years of struggling with mental illness and depression like her brother.

Alongside a picture of Angel and Aaron as kids, she wrote on Instagram: "I want to start by sharing how much I appreciate all the birthday wishes. While today is incredibly tough, I am overwhelmed by your love and support… thank you from the bottom of my heart.

"Almost 11 years ago, I lost my sister, Leslie. I remember feeling broken, confused, and I questioned how I was going to continue on without her in my life… And now, over a decade later, I am forced to once again deal with the extreme grief of the death of a sibling. This time, it’s my beloved twin, Aaron. We had an indescribable bond… and now… he is gone."

She continued: "It feels unfair… I feel too young to carry the weight of losing two of my siblings. When we lost Leslie, I was blindsided and shocked. With Aaron, however, we had tried everything. In fact, I spoke with him two days before he passed, and I begged, once again, for him to let us help. I did not know that would be the last time that I would ever hear his voice. And now, I sit here on our birthday, trying to navigate this unimaginable loss because of untreated mental illness and the addiction that it led to."

Angel and her family, including older brother Nick Carter, 42, have announced a benefit concert on January 18, 2023, called 'Songs For Tomorrow', to raise funds for the mental health initiative On Our Sleeves.

Angel added: "Aaron dying was the worst day of my life. I have loved him since we were born… it feels like a piece of my soul is gone. And yet, despite all this pain, his passing has lit a fire within me. I feel a calling and responsibility to help other families and continue the conversation to further break the stigmas that surround mental illness. And so, with the support of family and friends, we are planning a benefit concert to raise awareness for mental health, with 100 per cent of proceeds being donated to @onoursleevesofficial To learn more, please click the link in my bio to see how you can support the critical work of On Our Sleeves by attending “Songs For Tomorrow” on January 18, 2023, in West Hollywood, CA."

She concluded: "I have learned the pain never goes away and keep telling myself that it is one step at a time. I am hoping you can join me for this crucial next step… in memory of Aaron."