Please take your Mom to an Alanon meeting. It would be great for the both of you. You would understand why your Mom & Dad both do what they are doing.
Good link
http://www.al-anon.alateen.org/ but if you can't find a meeting - go to an AA meeting. There are spouses of alcoholics there too.
I grew up where both my parents were alcoholics. Dad died when he was 45, Mom had a spot on her liver - told to quit drinking or die. She chose to live & I got my Mom back from when I was a little girl.
Me? Would never touch the stuff. Seen what it did to my family. But I ended up in therapy for a year 20 years later. While in therapy I was to attend 6 AA meetings. There was something my therapist wanted me to see. I went to one meeting & wouldn't go back. I wanted to tell them all off & smack them in the face! I wanted to yell at them to quit thinking of themselves & think what they are doing to the kids. My therapist wouldn't tell me what I needed to see, trying to get me to go back there. I told him just give me another book to read instead I wasn't going back. I grew up in it & that was enough!
There wasn't any Alanon meetings close to me & then it was suggested the AA meetings.
With alcoholism over 90% of the time there will be abuse there as well. It would help your mother see that your father's drinking problem is controlling her as well. It would help your mother see what she needs to face.