I am so sorry that you are in this position, however it happened. You feel a responsibility to your Mother even tho the addiction(s) are most likely causing her behaviors. I think she has really destroyed the relationship by her negative comments to your husband about you. Sounds like she has been a huge problem for you and you have been just a nice, normal, hardworking student who means no harm. Professional help would be hopefully be able to assist you with these circumstances. Perhaps they would know of a place to go that would take her. I am praying for a quick resolution for you on this because it sounds like you are at your wit's end.
Behaviors like this from her have or will have consequences, such as not interacting with her for the foreseeable future. I was done when my Mother was at a celebration for my Daughter's college graduation at my house. I invited many of my own friends as well. She did exactly what I expected. My good friend who knew all I went thru to raise my children on my own and get a degree and work as well. My friend said, I bet you are so proud of your Daughter and Granddaughters. She told her that she was proud of her Granddaughters and left me out. I was fuming and decided that was the final straw and that I couldn't put up with her anymore. What a betrayal. The nastiness just gets worse. I feel your pain and hope you find some available resources to help as you are being harassed and abused. Much luck to you and God Bless!