Hi GregR.
I read your initial post, so I see you have two sons. And it sounds like your wife is painting you black in front of them and has threatened you with the police (DV). And you further stated that you have been more focused on taking care of yourself recently.

So, the change from summer to now: one thing many of us have experienced is that ANY changes in routine or structure are causes for distress for the pwBPD in our lives. So, the change from summer to school and the added expectations of possibly delivering/picking up kids from school, extra-curricular activities and so forth may be elevating the stress level of your wife.
You may never know the cause, but her outlet is you, which you have to stop. When you ask her to speak respectfully or not to hurt you or say hurtful things to you, it is, believe it or not, an invalidating statement for her. This is the crazy making of living with BPD. She is feeling hurt, so how could she be the one hurting you? That's how she will see it. So then, when you justify or defend or argue, it's off to the races because you are now denying her hurt.
The only way out of this is by refusing to play the game because there are no winners. And some ways of refusing are better than others. Validating her upset ... ."Gosh, I see that you are upset, and if I felt you were ignoring my requests, I would be upset at you, too." Then, boundary or your truth ... ."But this conversation is now upsetting me. I want to hear what you have to say, but I can't do that when I am upset. I am going to leave for 25 minutes. I will be back. We can talk then." And enforce ... .leave for 25 minutes of self soothing. And do come back when you state you will, so that you don't trigger the fear of abandonment that is often a source of so much of the anxiety running pwBPD's lives. If it escalates again, you repeat the process. Done enough, this process does lead to reduction of conflict and drama in the house, which is actually good for everyone. And, if she insists on putting your sons in the middle, take them with you when you leave. "I am going to go for a walk/drive with the boys. We will be back in an hour and can talk more then."
It sounds like you have been doing some of this for your self. And, it sounds like you are emotion coaching your sons to let them know it is okay for them to have feelings of sadness, anger and so forth.

That is exactly what they need from the nonBPD in their life ... .really important.
I hope this helps. Hang in there. And keep working on yourself. The saying on these boards is that you have to put your own oxygen mask on first before you can help anyone else. So, keep doing small things each day for your own health. I am so sorry that you are in this difficult position. It is truly painful. But you are stepping out of the FOG (fear, obligation and guilt); keep your head up because that takes courage and a lot of self honesty. My prayers are with you and your family.