How should I handle my mother in SNF who calls me almost every day to complain, argue and verbally abuse me?

She has been in SNF for 4 months which is finally nearby where my husband and I live, but she expects us to visit and bring her things all the time (some of which are not permitted). We recently cleaned out her apartment as she is physically and mentally unable to manage on her own and has many health conditions. We were driving 2 hours each way to visit her and then worked in her apartment until we found a wonderful SNF nearby us. Now she calls and freaks out when she wants something that has already been donated. I am not talking about jewelry, family photos or heirlooms, but things that she cannot use in her new residence or that are considered contraband. Her phone calls are mostly negative as she is very self-absorbed and has no regard for our private life and personal responsibilities. I cringe every time the phone rings because she is verbally abusive and demanding. A big part of the problem is that she wants to lives with us but needs 24/7 care and has acted very domineering when she has visited in the past, so we feel we made the best choice. I am her POA and have been handling all financial matters as well as being her health care advocate interfacing with doctors, nurses, therapists, dieticians, social workers, etc., but that doesn't seem to be enough. Thank God that my husband is in this all the way supporting me and treating her like a mother rather than a MIL. There is no one else to do this if we don't (she is divorced and my sibling lives out of state) and we are doing the best that we can. During the good times which are rare with her I don't mind and am happy to help, but then she reverts back to her mean self again. And she does not have dementia and aces all the cognitive tests. When in front of others she acts like we have the best mother-daughter relationship. Everyone thinks that she is wonderful and such a delight, but they do not see the narcissistic side that we do. Not once has she thanked us and said that she appreciates our efforts and has even accused us of mishandling her funds and her possessions. My life has been turned upside down and I am totally stressed. Any suggestions???