I am going through exactly the same thing with my mother. I am 27 and my mother has taken mild drugs since before I was born, stopped them when I was born, then started the drinking.
She has just fallen down the stairs last night, has a fractured skull and is staying in hospital tonight!!! I too, live with my mother as my stepfather was very nasty to her and I didn't want her to go through it on her own, as she has Fybromyalgia.
He has since left her as he was sick of the lying, cheating, affairs, denial and the amount of drinking combined with the pills was not pretty.
I am now trying to look after myself as I now realize that I cannot stop her drinking, I cannot even help her at the minute until she see's what she is doing, I am at my wits end and have run out of options other than to run away back to Australia, away from it all, but then I fear I will worry more as I cannot be there to see her and how she is, so will I then become just like her.
Just want you to know I understand, and if you ever need to have a moan I'm always here as I don't leave my bedroom if she is here, I am to scared of the guilt trips, conflict and saying things I regret. It is very hard and frustrating keeping your mouth shut, trust me, I know!!!