This is the experience. It's a mental disorder, there is disordered behavior.
If you want to be really ready for this, find a book on being with a BPD partner.
Someone else said something about boundaries. There are books on how to manage having a borderline partner like this one.
https://www.amazon.com/gp/product/B005JFB3OS/
A lot of this will be understanding, if you set a boundary, it will infuriate your partner, but that's normal, and that's the cost of having a pwBPD.
Learning to set small boundaries will help in a big way, I'd aim for that. The goal shouldn't be avoiding episodes, the goal should be getting her better skill to cope with doing stuff she doesn't want to do, and learning to be OK with being uncomfortable.
This book will explain why you're feeling what you're feeling and help you get out of that rut:
"Stop Caretaking the Borderline or Narcissist: How to End the Drama and Get On with Life" https://www.amazon.com/dp/B00B60DRKI/
I would suggest “My Secret Disorder” a book I found recently which explains the story of BPD in childhood through to recovery and what triggered them, what helped them etc etc.
I found a Dialectical Behavior Therapy workbook helped me the most. I see my therapist weekly and we discuss my personal and social issues but the book helps me understand my cognitions, behaviors, traumas, and responses. Even my partner without BPD likes this work book just as a constructive way to understand yourself and learn to cope. I linked mine below, the same book comes in options like for anxiety, for anger, for bipolar and so on i happen to get the for PTSD.
The Dialectical Behavior Therapy Skills Workbook for PTSD: Practical Exercises for Overcoming Trauma and Post-Traumatic Stress Disorder (A New Harbinger Self-Help Workbook) https://www.amazon.com/dp/1684032644/ref=cm_sw_r_cp_api_i_rNrHFbDKB2ANV
You're not in a great position if I am honest.
You have anxiety and he is a trigger, and BPD takes a long road to recovery, and to be honest, you need to be able to put up a wall and be a strong person to deflect the emotional swings of BPD - otherwise they will be demoralising and hurtful. This wasn't easy for me to start, but through studies of BPD and it's behaviours, and conversations with my partner, I was able to see the warning signs, attempt de-escalation or remove myself from the conflict if need be. I was able to do that because I don't have anxiety.
I am sorry to be honest, I think the fact you do is really going to make this impossible to move forward with, especially if he is not in DBT therapy already (and even then, the progress to make on that isn't easy, it takes time and requires constant effort from you both).
I would consider maybe taking the hard short term road, of focusing on your own mental health and well being first in this situation as you are in a position where you can't focus on yours and his together.
However, that being said - if you are wanting to try push through this (and I love you for that), you need to be firm, and put conditions down, you need to build a stable framework in order to get him into DBT and ensure the DBT sticks. Stability is King in a relationship that involves BPD.
There are some books you can read, like this one: Stop Walking on Eggshells - which will give you the tools to be firm, and help encourage the normal response behaviours one should have (rather than BPD reactions).