Welcome to SR, Kim. There are many people here with long experience of addiction and recovery and they will be along to give you helpful feedback.
I just want to say I am very sorry for the emotional anguish you and your daughter are both experiencing right now. Your daughter's father is dying, and perhaps some grief counseling for her would give her a safe place to feel and express her grief. She may not be comfortable to be truly herself with you, in part because she may want to avoid upsetting you while you are already upset.
My father died of cirrhosis when I was 13. He had been missing since I was 4 and I did not know him as a father.
I know that for myself, at 13, it would have made things much easier had someone given me something to read about alcoholism so I could better understand why he abandoned me and why he was dying. Perhaps in grief counseling, your daughter would be also helped with some information about her father's disease.
Since he is your ex, your daughter already feels conflicted in her relationship with her father and with you. This is the natural outcome of any divorce, of course. It is no one's fault. But it could make her hesitant to rely on your fully for the support she needs.
It is a devastating experience for a 14 year old girl to see her father's body and brain dissolve before her eyes. I am so sorry for her. And your pain in witnessing her grief must be devastating as well.
God bless you both and send you angels in your lives to comfort you.