Mother was financially exploited, manipulated, brainwashed by sister who is now bullying me. Is there anything I can do?

My poor stressed mother has recently passed and was financially exploited for complete frivolity living above means, by my sister living nearby her for years. Sister then felt completely entitled to intimidate & bully me each visit for obvious reasons, sometimes upsetting me so much to fly home early, note I live abroad. She brainwashed my vulnerable mom that I was a troublemaker & sucessfully got my mother to refuse my calls for many months during her last few years fighting cancer. I did not stress or hound mom throughout, but channelled my outrage to my oldersister after receving intermittant breakdown calls from mom when sister would seriously not return credit & bank cards, more extreme fin'l abuse, fights mom had with sis. Mom & sis would later deny to my brother that moms random cries for fin'l abuse took place, obviously mom's arm twisted manipulated, complying or social visits would stop etc as punished previously. I cannot mentally get over sis getting away with cutting mom off from me successfully to cover her greed & inflict pain nor brother's lack of action or wanting to address obvious financial trail supporting abuses but most of all bullying & severe mental pain caused purposely to me for years by sociopathic sister. We are at stage of Estate finalising. Brother does not want to lose social activities with nearby sis & family. Any advise would be gratefully received.