Part of me could see right through her. The lies to build herself up... . it was like a transcript of what she did to me... . but I still left there beaten down and overwhelmed with grief. I now know I cannot attend any of the racing events I used to... . It's just not healthy for me to be around her at all.
That was a tough test for you. One that you went through and came out of it with a confirming thought - realizing that seeing her right now still hurts.
The fact that you could understand what she was doing - seeing through her - is a start. You may have still had some emotion about it, however, in some way, this is progress. Learning about BPD here and starting to see the patterns. The next stage in the detachment process is to use that information and work on not taking her actions personally. She is who she is and will continue to be this way. You cannot change her, you can only work on yourself.
We have a workshop here about using your 'wise mind' - meaning, balancing out a situation by using what you know and understanding the emotions that you are experiencing, to make wise choices. Your post is an example of this - you understood her behavior, you explored your emotions, and you made a decision to not go to the races again. It doesn't mean this is less painful, eventually it will be. You can read more about 'wise mind' here:
https://bpdfamily.com/message_board/index.php?topic=64749.0