My sister was appointed guardianship over my mother. She would not let siblings help her. We never knew where Mom was. How to cope?

There are 6 siblings. We were never updated where Mom was. Phone calls were ignored. When we did find where Mom was, we were asked to have a escort to see Mom. The court requested updates on her finances and to be put in the court file. None in 8 years was ever there. Two of the siblings live out of state and have a great deal of influence to the guardiian.
The three of us that live in the state with my Mom are in the dark most of the time as to the whereabouts of Mom. The guardian moved into Mom's house and allowed her boyfriend to live there also. Why is this guardian acting like Mom is only hers and treats her like she is property. I have visited my Mom several times without the guardian knowing. Mom suffers from dementia and Parkinsons. Sometimes she is coherant.
She always recognizes me and acts afraid of the guardian. Mom is convinced that I stole money from her and that another sibling is living in her house and that another sibling put in the nursing home. Mom voluntered to put herself in the home after a discussion of where were 66 pain pills that were unaccounted for. During this time, the caregiver was missing in action because she was securing a relationship with a cousin. That cousin is living in Mom's house and they plan to marry. Why is this caregiver acting like she would have to share Mom and we don't exist. Now I find a will has been written by Mom. Another sibling from out of state took Mom to an attorney and let her fill out a will. This is going to be a nightmare. Since Mom was judged an disabled adult with severe dementia she could not sign anything of make any legal issues on her own. She was assigned a guardian ad litem for this purpose. No one informed the GAL of this action. It breaks my heart to know that Mom belives untruths about siblings that are kept out of Mom's life. Myself and two other siblings were original guardians and resigned when we were accused of so many lies. We thought that we could take care of Mom by visiting her and making sure her needs were met. Mother was a hoarder: Myself and two other siblings cleared out her house and plan to bring her back to a safe home free of clutter. The caregiver did not help at all. Instead she spent her time with her new relationship and her job. The caregiver has 3 children in this state.
She involved the 3 children to help her. All the accusations were unfounced in court. As the financial person, I had a receipt for every penny of Mom's money. Mom had 3 aol accounts; paid for insurance on a car she hadn't owned for 4 years; wrote large checks to utility company and never sent them (thank God she didn't owe that big of amount). It was a nightmare just getting Mom's bills figured out. Never did I expect any money for this. My other sibling was appointed temp guardian. She kept Mom in new clothes which helped Mom's mental outlook. The last of the siblings would live in Mom's house and takie care of her needs in exchange for room and board. Everything was running smooth until Mom convinced the persent caregiver allegations agains the temp guardians. I am angered that this is happening. And further things like not seeing Mom has added to my anger. I have even called the caregiver at her full time work and she tells me she cannot talk. The caregiver and boyffriend have lived in Moms house off and on for 8 years. For three years they have moved in completely replacing Mom's things with their own. They have not paid rent and have had to put a mortgage on Mom's paid up house to pay for medical expenses. I have tried to talk to her boyfriend which happens to be our first cousin, and he hangs up on me. On my Mother's phone. She is blinded, or I like to called brainwashed by her caregiver. Is this a control issue? We had one sibling die unexpectedly. When we gave a memorial service Mother was there in a wheelchair. I asked her if there was anything I could do for her and she said she wanted to see her children. I found out that Mom was yet in another nursing home due to a broken hip. I wheeled Mom up to a church pew by me and talked to her about how sorry I was that she lost a daughter. The caregiver saw Mom talking to me and came over and removed Mom and sat down by her. I can clearly see what is going on here. But what can i do? I am not going to waste money in a lawsuit since the caregiver brainwashers mother and that would be useless. Oh and I am disabled by diabetic neuropahty. Even though I took care (straightened out Mom's financial mess) and during this I took care of an infant. What is our recourse. The caregiver lies to us. when confronted she has an excuse. All the relative think that the caregiver is doing an excellent job. I have realized that my Mother is the caregiver's puppet. As far as I am concerned Mom left us a long time ago when dementia started to take over her life. What can I do to right things and take the control away from my sister (caregiver)