This may be a bit harsh.
How long are you going to enable her behavior? Why are you staying around to enable her behavior?
Where is she getting the two beers she drinking a night? Why aren't you tossing out any alcohol that comes into the house?
She has a drinking problem. Period. You're making excuses like you are accusing your uncle of doing if you think the color or type makes a difference.
You took her to the 'bad side of town' for coke and got beaten and robbed, but blame her because 'she made me'. You made a choice that you seem to know was a bad one to make.
Sorry, you have to take responsibility for your actions and get out. Staying is only keeping the problem going and growing. You can't 'fix' her and building up resentment against her when you know you should have gotten out months ago doesn't help either one of you.
Let her go to figure out that rock bottom hurts. Give yourself permission to let go and move on.