Now that all of the hard work is done, my sister wants to undo all we have set up for my dad by sabotaging and making untrue accusations. What do I do?

My Father and Step Mother lived in AZ. In Nov 2017 my step mother had a large stone break loose and crash into her Pancreas destroying it and putting her on life support. I am married, my last child just graduated from HS in May. I supported Dad long distance through struggles loneliness and stress, waiting for him to tell me he was ready for me to travel to AZ. My Dad thought she was improving one day and accused the hospital of trying to kill her because they were poor the next. A health care friend helped get her moved to the best facility in Scottsdale. They determined her prognosis was not good. contrary to what my Dad wanted to believe. Showing signs of dementia, his memory was terrible and bill collectors callied his house 24/7, because at 76 he had never really had to care for himself. My Step Mother has two children and several grandchildren. The health care facility had no clue because none of them visited or called. They thought I was my Dad's only child for the same reason. My father finally asked me to come out in May. For 2 weeks I stayed with him and worked remotely. His house was a disaster. Three year old expired food in the freezer, refrigerator and pantry, rotten food that had turned to liquid bacteria on the pantry floor. The bathrooms hadn't been cleaned in months. He allowed their small dog to urinate and defecate in the guest bedroom so long it was ground into the carpeting. The house was closed up and saturated with cigarette smoke, dirt and dust. As a pack rat, he had hundreds of magazines from 1970 to present that he never read, broken and unusable items filled drawers and closets, etc. During my stay I cleaned and threw out old food, had carpets cleaned, disinfected everything while working a full work week from 0300 to 1100 M-F to be available for appointments the rest of the day. Medical appointments, bought him new shoes, new clothes and had difficult end of life conversations with him, got his legal paperwork drawn up for POA both medical and financial and a living will. My brother lives in AZ and has no relationship with my father or me. I have a terrible relationship with my narcissistic, abusive sister, but advised her of Dad's situation if she wanted to work together for his best interest. She told me no in a very vulgar and demeaning way and advised me she didn't have any money. I told her he needed more care than just money. Dad shows signs of dementia, forgets to take medication, angry outbursts and can't manage money. When meeting with the Doctor and care givers, they pleaded with me to help my father understand the severity of her condition. Her body was failing on all levels, they were treating her for painful infections constantly. She was a strong and proud woman. I knew there was no way she would want to live on a feeding tube, ventilator, unable to talk or go outside, laying in bed with a tv screen shoved up to her face 24/7. When I visited her she was very happy to see me. I showed her pictures of my sons and the most recent paintings I had painted (she was my biggest fan). I read to her and did crosswords in front of her (her favorite). I told her I was taking care of Dad and she was very thankful, mouthed she loved me. I told her I was there just for her and asked what I could do to help. She darted her eyes toward the ventilator and squeezed them tightly in sadness. I asked her if that thing bothered her and again she squeezed my hand and her eyes tightly and nodded. I asked her if she wanted me to do something about it and she nodded, mouthed thank you and she loved me. I tried to get her kids to come from California and they were too busy. They made terrible accusations about me on Facebook and the doctors of killing their mother. We gave them ample time to come to the hospital but they didn't. My father didn't want to be in the room while they removed life support. I convinced him to stay. I told him he could go out to the waiting room if he wanted, but I promised her I would hold her hand and be with her every step of the way. They moved her bed to the window, per my request so she could see the trees and blue sky (she loved animals and nature). She passed within 15 minutes after disconnect as my Dad and I held her hands and each other sobbing. I took care of the death arrangements alone and a small balloon ceremony with just me, Dad and the dog. I had to move him to Kansas, got him an apartment he could afford and set up doctors, health care plans, got him glasses and prescriptions, etc. We brought the belongings he couldn't live without, furnished his apartment and clean weekly. This whole ordeal cost us 7k. I cook his meals 4 times a wk, pay bills and give him spending cash. I got my sister to take over the house cleaning. She uses the time to criticize and sabotage Dad and my communication like an ex wife trying to poison children against their father. She used to accuse my Step Mother of trying to kill him, so they did not get along. What do I do?