Thank you all for taking the time to read all of that. I understand that I can't change my dad's actions. It's just so frustrating to see him like that, especially when he's aware of what he's doing to the family.
I just don't want my mum to be so unhappy. I'm not sure why she won't leave him. It could be because she's scared of being alone after 29 years, because she truly believes he will change or because of what the family and community will think. I'm Indian and although both my parents moved to the UK when they were infants, keeping up appearances seems like the best option rather than actually being happy...which is weird because everyone in the family knows my dad is an alcoholic now. He wanted them, my mum's side especially, to know so that we would be embarrassed. But it doesn't.
Now my dad has no licence my mum has to drive him everywhere. He loves it, he doesn't care because now he doesn't have to worry about being caught drink driving. He even dislikes the police because he thinks they wronged him!