Welcome bythewaterfront: I'm sorry about your situation with your wife.
My understanding is that some therapist make a point of taking a little time to talk to partners separately, during the initial stages of couples therapy. If this doesn't happen during the first session, and it isn't mentioned as something to take place during the next visit, then you might want to request it.
The link below can give you the perspective from a couple of therapists on:
Talking to Our Couples Therapist Without my Partner PresentYou might want to ask your therapist about whether they have experience with treating clients with personality disorders.
I have separated from her for the time being bc I could not take her rages in front of the boys. My attorney also recommended I move out to avoid being arrested for false allegations made by my wife.
 :)oes your wife get physically abusive with you? Has she threatened to call the police to make false allegations about you?
Last note, my wife always mentions to therapist that if there is nothing wrong with her then why am I the only person she treats so badly. This is a difficult statement to respond to without having to go into terms like "narcissistic supply" and all conflict is covert/hidden from friends, fam, colleagues.
It seems to be typical that people with BPD tend to hold onto their bad emotions and then unleash them where they feel safe, usually at home with a partner.
This lesson on
DON'T INVALIDATE FEELINGS should be helpful. For people with BPD (pwBPD), it can be important to NOT invalidate their feelings (by word, expression or body language). Their feelings may seem senseless, but they are their feelings. You don't want to validate invalid facts, but sometime you might want to progress from NOT invalidating to offering some level of validation of feelings.
The link below will take you to a section with a series of lessons you should find helpful:
Lessons for Improving a Relationship With a Borderline Partner