How to help my mom with benzodiazepine addiction (long but please read)

My mom and I got into a huge fight today because we went to an amusement park and she took 3 ativan (lorazepam) tablets, and then later on drank rather excessively. And I got nasty with her and “embarrassed” her in front of the rest of the extended family… which may not have been the best move….but I am completely FED UP with her drug behavior. I study pharmacology and I know that the side effects of these class of drugs are extensive and often permanent. I believe she already has brain damage as she cannot remember things and just makes things up that she thinks happened. She’s a smart woman but over the past few months her cognitive function has declined. She is terribly unhealthy and I am concerned as she is only 45 but her health and mental status are making her seem like an 85 year old with Alzheimer’s. Her sister killed herself years ago and I honestly think that’s the same path she’s on. But whenever I bring up concerns with her she thinks I’m attacking her or “being mean” to her. I am not perfect (I have my own mental issues) and I tend to have a sharp tongue which I am working on. But she always thinks I’m out to get her and that I hate her. I need advice on how to help her before she’s gone. I don’t know what to do any more.