How do I deal with a screaming 86 yo mom I live with who's understanding has deminished? She interprets normal conversion as attacks.

Thank you for your answer. My mom is high functioning in that she's been driving everyday. She is out every am by 6:20. 365. She meets a friend or two and they hang out until the stores open. Then she goes to at least 2 stores, sometimes several, where she buys things such as groceries and clothing and household items that are marked down. She does this 7/365. She buys things we already have multiple of. She won't get get rid of anything. She brings straws, napkins home despite the places she keeps them overflowing. She saves all plastic store bags. She's very clean but hoards. I'm a nurse, retired. My son's an attorney. Nobody in family will deal with her. She has been this way ever since I can remember. Over this past year I see her becoming forgetful and having trouble feeling she is "following the rules" which means her incorrect understanding of certain forms she fills out yearly. But along with this she is even worse in how anything I say seems to immediately throw her into terrible verbal abuse toward me. She WILL NOT STOP SCREAMING long enough for me to complete a phrase let alone a statement. This isn't new but it's worse. Her words are terribly abusive. I do leave but I'm tired and just want to rest. My entire life was difficult being raised by her being this way. I had no brothers or sisters to talk to to understand she was ill so I had major struggles feeling so unhappy and inferior. I'm finally mostly emotionally healthy now, finally. She has no trust. She preached to me since childhood to never trust anyone but I'm trusting and joyful. She appears friendly to all outsiders. She will never consider POA of any kind. She needs me now but she's making it so much more difficult. Thanks again.