Hey boohead: I can hear how frustrating it must be for you. Check out the two links below and give the strategy a try. You have to set a consistent boundary with her. It can take time to get a desired result. There is a link to info. about boundaries in the margin to the right of this post (under, "What is the first step" - Basic Tools)
Perhaps you might want to think over some recent discussions and think about what boundaries you could have set. Then start enforcing a boundary during an upcoming conversation. It might feel a bit awkward at first, but if you stay with it, you will likely gain some benefit.
Check out the lessons below:STOP CIRCULAR ARGUMENTS - DON'T JADE (Justify, Argue, Defend or Explain)https://bpdfamily.com/message_board/index.php?topic=118892.0;allENDING CONFLICThttps://bpdfamily.com/content/ending-conflict