I feel so freaking alone. Any advice?

I'm new here, I needed to find some kind of outlet because I do feel so alone. I've been taking care of my ma now for over 4 years now. My father passed after a long battle with copd and my ma and sister really were the two that took care of him, my ma 24/7 as well as the family business. My sis, although helped quite a lot, she had not lived with the two basically, barked orders at doc appts ect then went home to call me and my little brother to basically complain we weren't there. Anyway, he passed, and because of family drama, I was booted out and chose to moved out of state. I came back to make sure my father's grave stone was finally taken care of then boom ...went to ma's doc appt and her doc knew but was waiting to inform someone of her illness....my mother has dementia, and if she has some kind of change, whether it's a med change or something such as a uti, she becomes VIOLENT....I've been pushed down stairs, punched, kicked and bit and have had items thrown at me. Shes hit me with boards, pulled down blinds and smacked me with them and has grabbed and squeezed my hands to the point she broke my finger. I've got psoriatic arthritis severely and have no joints left within right hand and it gets rough. Nice been called everything but a human being, told she wishes I die and that she f*** hates me and wished I had never been born!!( Not even close to who she really is or was) I'm with her 24/7 and just recently signed her up for day services but even they have called me to come get her early. Both my siblings have witnessed some of the verbal and physical abuse she has done to me. One time when the cops were called, I ended up in the middle of the road in cuffs because she was freaking out, jumped from the truck and ran screaming I was trying to kill her, but even so, neither have EVER stepped in or asked if they could help. Both say " if ya need anything" and after several times asking, I'm done asking. My brother has taken over the business and has basically took over and away all moms financial EVERYTHING!! He doesn't have power of attorney, never asked me nor my sister about anything. Nothing about what he was or had planned just took my mom to his lawyer and lord only knows. They set up a trust a year after she had been diagnosed with dementia. We had a family meeting before my dad passed and he wanted my brother to buy us out when something happened to my ma, because he stated " his legacy was our inheritance" and he had 3 children not just one. As well as a wife that would need cared for. Now I'm paying for her day services just to get a break 2 times a week for 6 hrs a day and I have just my disability ck to live on.....I seen his email to the lawyer before I moved after my dad passed about how he wanted in the paperwork to state some specific way so that when my mother passed basically, we can't go back on him for anything with regards to the business ect. He made her retire, took all her credit cards banking, everything and tells me I'm to not open any accounts and only get cash for her needs from him or the bank account that he has his name on. It's a very long story but it's starting to come to a head! While he and my sister are off hunting africa, going to Hawaii paying off houses and family trips to Disney Land, I'm either at the hospital with ma or in transition from the hospital to home and getting the tar beat outta me to keep a promise to my father to take care of my ma, just 3 days before he passed! I called on my brother and sister this last time she tried breaking the glass out of the door to leave( cuz when she as a uti, she get violent) and my sis didn't answer and when I finally got hold of my bro, he was to far away working on his 60 acers he just bought planting some feed for hunting season in october....that's when I said forget it......I'm alone and don't know what to do!!! I want to take her on a vacation, while she is still able but not gonna happen due to not enough funds.......it's just sad