Hi and welcome to the board! I am so sorry to hear about your struggles with your sister and also that your mother had a stroke. The actions your sister took are very very hurtful. You have found a place where a lot of people can relate to having a mentally disordered family member so you are in good company. We all support each other as we navigate our way through various situations.
I hear you using terms like cluster B and energy vampires. We don't use those terms here so forgive me but are you saying you think your sister has BPD and or NPD? I just want to make sure we are talking about the same thing and don't want to make assumptions. There are a lot of pop psych terms out there that don't really convey what is going on, which is in part why they are not common on the site.
I am glad you got yourself a therapist to talk with. What you describe is a scary situation and it is good you have help. We also have a Legal board here that many people have found to be of benefit. A lot of the posts apply to Divorces from BPD/NPD but they also know a lot about how to handle these high conflict personalities in legal situations. In case you want to post there and ask for support or questions here is a link:
https://bpdfamily.com/message_board/index.php?board=10.0In the meantime, feel free to settle in, ask questions, read and post. We can help you as you deal with this tough situation.