Hi Cyqueenzstyle and

I'm a doctor (resident) who dated this nurse for over a year and had the typical experience (idealize/splitting/Devalue/push pull/ high/loss, losing myself and self worth, addicting hot sex, unwanted pregnancy and abortion, cheating and lying about cocaine use.
One of the most confusing aspects of this disorder (in my experience), is how a person with BPD (pwBPD) can be so high functioning is some or most contexts (i.e. professional life), and yet have such dysfunctional/disordered behavior in other specific contexts (i.e. that of familial and intimate relationships).
Also, I think addiction behaviors (i.e. cocaine use) can serve as camouflage for the personality disorder. PwBPD seem to have less issue identifying with problems such as Bipolarism, or addiction... .but if you try to tell them they might be suffering from borderline personality disorder then they will shoot the messenger and the messenger's family.
She couldn't give me the satisfaction at the end of saying she'll be my girl officially for more than two weeks before breaking up again. So now we've been no contact since December 21, 2016 with the exception of silently seeing each other on passing in the hospital.
This is another aspect that took me a long time to grok. My best model for understanding this behavior is to imagine pwBPD as suffering from a kind of PTSD. Only instead of reliving specific memories, they are re-experiencing the feelings associated with their trauma. And as I see it, sometimes their actual trauma can be imagined if not real (some sufferers seem not to have a traumatic background). What triggers their PTSD is being in intimate and familial/familiar relationships. Relationships that trigger them more (maybe more intimacy? maybe more familiarity?) evoke more trauma and more disordered feelings.
So on the one hand, she really did want to be your girl, to be the mother of your child, etc... but all that intimacy/familiarity cost her. In her mind, it made you the cause of all her pain. But only because she had projected all of that buried trauma onto you. And this is why you could never be "official" for very long.
What can allow you to associate with a pwBPD with minimal issues are (emotional) distance and formality.  :)on't be too close. Don't dismiss.
It ended with her dad (divorced after cheating on her mom nevertheless still the apple of her eye) telling me that if I contact her again, he'll call the police. This was in response to me reaching out to him for help in caring for her use of cocaine which I hadn't realized was nearly as frequent as it is. He weirdly flipped his anger on me.
Maybe her father has inappropriate anger. But maybe she communicated a very different picture of your relationship with her father. Think "distortion campaign." Sometimes it's lies. Sometimes it is their experience reimagined in a manner that relates to the source of their disordered feelings (i.e. original trauma). You don't know. You won't know. Only her dad knows what she told him. Maybe someday you'll find out. Probably not.
Her father has spent all her life trying to figure out how to help out her daughter... .unsuccessfully. You probably have a better understanding of her issues than he. Family members of pwBPD have parallel but different issues with disordered family members; take a gander at the "children/relatives" sections of the board and you'll see.
Family members can be in greater denial than people who only date pwBPD.
I became desperate to the point where I even put a ring on her finger and it still wasn't enough to keep her from the back and forth... .
So now we're done and I don't expect to ever hear from her again and I'm wondering if my grieving will end and my mourning will eventually cease and I will go back to normal.
I think you will need to grieve over the relationship you thought you had but did not. And you will need to grieve while knowing that the person didn't really die but is still walking and talking around your life -- this isn't easy. There is finality in death. And in a more "normal" ending of a relationship, there can be mutual understanding. Here, you'll find none of that. What you need is to find a way to reconcile all the various cognitive dissonances that are dancing around in your recollection of this relationship.
You are in the right place.
Best wishes,
Schwing