Siblings accuse me of things that I did not do. Advice?

I have posted before on my siblings' behaviors but they still accuse me of things that I did not do. I guess it is not going to stop. Recently my brother accused me of banning them from picking up momma in assisted living. It is allowed now. He sent me a nasty, ugly text message saying that I was making momma unhappy and I am taking everything away from her. I think momma complains to him and does not understand the logic behind these rules but I am the one that gets blamed and shamed. The scapegoat. Brother is the golden child. I did not do such a thing. I did ban them from seeing her in her apt because they were bringing in bed bugs for seven months and we spent over $7000.00 in the process. I was tired of driving over 5 hrs each way to clean them up but that has been a rule for over a year and a half. Recently was also accused that I was going to override the will and not give them their share of the inheritance. I don't know where they come up with this stuff but I cannot do that legally nor would I. There have been other things that I will not list because it is a long list. I have medical and financial POA for momma and her main caregiver for 10 years now. I have never received any help from any of them. I don't have any contact with my neice because she spent all of her college money up in a year and a half and we did not give her any more after she asked so she is mad at momma and me. Neice sent me nasty, ugly text messages - I guess she learned that from her dad. She won't go see momma when they were doing window visits. It has been almost two years and she has seen her once. This was before the virus that the college money thing happened. Husband and I do not drive over for Christmas anymore because of an incident that happened two years ago. I do have some contact with my sister and of course I talk to momma every two to three days and try to go see her when possible. I even drive 5 hrs over there just for a 30 minute window visit. But my brother, his wife and my neice have all been very cruel. I know - I can block their text and phone calls. Since we lost dad and momma made me financial POA it has been like this but now it is like 100 times worse. Every year it gets worse. Is it because they are getting impatient on waiting for momma to die so they can get their money? Money has always always been an issue. I don't have a family anymore. Oh - get this - momma takes up and lies for all of them. Being doing that for years. Even before we lost dad. During the bed bug issue - one incident I was washing 5 huge bags of clothes, taking care of an 86 year old in a hotel, drove her to all of her favorite restaurants and all she did was complain the whole weekend. She lives in one of the best assisted living facilities in the city. That was when I put a ban on siblings and no sooner than I got in the car to drive back to Atlanta - momma went downstairs to talk to somebody to allow brother back into the facility. Six weeks later. Nurse calls me. Momma has bed bugs again. Facility has brother on camera sneaking into facility up to mommas room. I told nurse he can clean it up and charge him the $475.00 cleaning fee. Momma lies and defends brother left and right. She even called my uncle and wanted him to reprimend me and then call her back and tell her what was said. Momma tells me "you seem to forget who the momma is". No I have not forgotten but that does not mean that I am going to be treated like that! Don't care who you are. This is only part of what I have been dealing with. I know how this sounds but I dread the part that I am going to have to deal with siblings after we lose momma - I am her trustee and also the executor of her will - but I will be glad when it is over. So tired.