In all situations like this, it's not your fault. So, it is good that you didn't seem to have written that down in your big post. Good that you see she needs help (or changes).

Now, you may want to try to understand what happened to mom as she went through her alcohol and drug years. Brains change. Alcoholics can have rage-issues - anger issues that are brought out when they drink. On top of that, the drug issues of the neighbor can impact brain function. I suspect she has somewhat damaged her brain to the point of affecting relationships, including yours.

I was close with someone who is an alcoholic. Her one bad trait. She would be "sweet" during the day but she would drink a bottle of wine and turn into a anger-driven person who was just impossible to talk to. When you love someone who is emotionally changed by something they eat or drink, then you need to just realize that you need to protect yourself with boundaries and stick to it. As a child of a mom - it's hard to do the right thing since you know they support you, give you a home and feed you. I was "under my mom's spell" for the longest time knowing she would pay for my schooling, feed me and all that - and I had nowhere else to go. She was not abusive, just thought differently than I did and we didn't agree on important things in life.

Seek out strong friends or even school-sponsored help if available - just make sure you know that it's up to you to strengthen yourself against falling into the same traps she fell into. You do sound like a great person and you'll get through this.