This kind of thinking has kept me in this doomed relationship for 15 years.
Perhaps... .
The one thing I like is "this kind of thinking" which was tied by to you explaining how you think. So... pretty clearly you have taken responsibility.
My hope and prayer for you is that in a few months you will say "I have chosen to stay in this r/s for 15 years"
Many of us nons (me included) can get into thinking about ourselves as victims that are being "attacked" by a pwBPD... .and that we are powerless to defend or save ourselves. Unfortunately in many cases... .technically that is true. If we are victims we build up resentment about others (the persecutors) and eventually lash out at them.
If we are
responsible for our own choices, then the focus is turned to us, vice the pwBPD. The good thing about focusing on us is that we are 100% in control of our choices.
Look, years ago I would lie to my wife (bad FF... .bad! ) and say things like "I don't know anything about X", sometimes she would figure out later that I did know about "X" and she correctly figured out I was lying my a$$ off to protect "something". That fueled paranoid fears.
My decisions damaged the relationship... I'm 100% responsible for that.
Once I got straight in my head that I am valuable enough to have privacy and to "enforce privacy" and to "stand up" to anyone that would seek to take away my privacy... .things started to improve in my relationship and in my life. And yes... .I freaked out my wife.
Basically... .I thought of myself first (in regards to privacy) and was unapologetic about itShe accused me of being a "selfish a$$hole". That was pretty easy to validate... .as it was true. (the emotion... )
Now I would say something like
FF wife (harsh and probing):  :)id you talk about me today at your appointment with P? What did you say?
FF:  :)iscussions with my P are private. I'm willing to set up joint time if there are things you would like to ask or discuss.
If she asks in more of a musing way... .vice "demanding to know".
FF: Boy (ff wife name), those sessions last about an hour and we cover a lot of ground. There's really no way for me to accurately recall everything we said, so it's best if I don't try.
See how the second one is a little softer? There are times when I try "softer" when she is demanding. Sometimes it inflames her vice shuts down the probing discussion.
This is wear experience and "practicing the art" comes in. When there is a musing (yet probing question) the goal is to not "ramp it up". Soft is definitely called for first.
When a demand is out there... .it's hard to know if "validation" or "soft" will work, but you know for sure that this line of question needs to be done.
Hope this makes sense.
Split up the issues... .big boundaries between issues in your mind and in your life.
If you like to look at porn, that's your business.  :)on't involved others (including your wife) in your business if they don't respect and value you.
FF