Is my mother an alcoholic?

First of all a little information: my mother separated from my father very early on and he sees me every Wednesday, sometimes on other days too. Yesterday I was with him the whole time and when I came back at around 8:30 in the evening my mother had already drunk 3 cans of beer and half a bottle of wine. She gets really annoying when she's drunk and shouts at me straight away when I tell her, "Mom, please stop" or "could you be sorry?" yesterday I didn't feel like it any more and wrote to her that she should stop drinking and that otherwise she would die. Then I told her that I didn't love her anymore anyway and well then she said that she would strike me out of her will if I carried on like that. And what she did yesterday is something I've been going through my whole life. I can understand why my father split up with her. Did I overreact yesterday? One day I woke up, lay in bed for about an hour, and then it was around 12 o'clock. I wanted to go to my mum because I was hungry. I saw two empty bottles of wine and a beer and her smell all the way to the bedroom door. During the course of the day she drank another 2 bottles of wine and 5 beers and she tried to strangle me when I told her to stop and that's not an isolated case. They drink a lot every day, usually a bottle of wine and a beer. I'm going to my grandma's in the next few days. I'm sure my mum has a problem. What should I do?