Is this a bad mother?

You're mum is being a bad mum, but no one intends to be. She sounds like a demanding woman, and the fact that her husband left her is obviously very stressful and that's caused her to decline into the comfort zone of alcohol. When you have two kids you're kids MUST come first, and she should realise that you are more important. If she loves you she needs to seek support, as do you. It's not fair on you and your brother to be in that situation. You are young, you need someone to look after you, not the other way round. Speak to you're mum about alcoholic anonymous. If she doesn't listen or kicks off speak to someone you trust, like a teacher, asking them what to do. You seem to have had a really bad life recently, and I genuinely feel really sorry for you. Don't pack you're bags yet though, and stick with your brother. Is there any other family you can stay with, potentially not your dad if he's that ill, until things cool at home?