Hi The Cookster, its true that communication with a pwBPD (person with BPD) can feel almost impossible at times and completely one-sided.
Have you picked up
Stop Walking on Eggshells or
I Hate You, Don't Leave Me? I found them very helpful in getting into my wife's headspace a little. It didn't change the communication dynamic much, but I felt much less frustrated about it and found I had more options than I thought.
This skills workshop also has some very helpful information to get started on improving communication:
https://bpdfamily.com/message_board/index.php?topic=143695.0Actually I've found these principles hold true to just to anyone, not just a pwBPD.
Hope this helps.
~ROE