I am so sorry you are going through this. It sounds like both you are your mom are really suffering. It is not good for her to keep you high, especially if it is leading to feelings of humiliation. It is not backstabbing to walk away. You have a right to make your own choices even if they disagree with hers.

Is there anywhere else you can go when you get into arguments? A friend's house maybe, or somewhere where you can cool down and won't get tempted to use?

You deserve so much better! You are stronger than this.