Nowwhat54,
I'm so sorry that you are going through this. I think one of the things that brings us all to this board is a sense of helplessness. I hope that, like me, you will be able to find the hope and support necessary to move forward.
As I see it, you have two productive options, neither of which may seem desirable/possible at the moment, but may be worth consideration.
1. You can move away (figuratively and literally) from your girlfriend so that you can focus on healing and strengthening for whatever comes next. "Whatever" could be singlehood, another relationship, or even potentially reopening the door for a renewed relationship with your girlfriend. This option has a lot of challenges:
Dealing with the threat of suicide - I'm currently being coached by my therapist on how to handle this with my hwBPD. I have not had the opportunity to "confront" the issue with him yet, but when I do I think it will sound something like "I care about you, so I would be deeply grieved by your death, but I understand that suicide would be a decision and action only you have the power to make, so I would not feel guilty. Our boys and I would grieve for a time, but then we would move on. I would probably remarry, and I would look forward to seeing them find wives. I would still be here to enjoy my daughers in law and, in time, my grandchildren."
Removing temptation - It's not the same, but I ended an affair 3 years ago so that I could be true to myself. I had to remove every excuse to go back to my affair partner. I changed jobs to make sure that I had minimal contact with my affair partner. It meant sacrifices in other areas of my life, but I recognized that I was not strong enough to resist that pull. And if I didn't resist that pull, I would continue to betray my true self and ultimately lose myself in the relationship. I know it may be hard to hear, but if you really want to sever ties and be able to focus on being the kind of person that can unapologetically ask to be loved, you may have to make some short term sacrifices, like finding another job.
Learning who you are - 3 years is a long time, even for someone as old as me.

For 3 years you have been defined, to some extent, by how your girlfriend sees you and the role that you have held in your relationship. It may take more than just leaving your relationship to help you define who you are. I had to leave my marriage (physical separation) and face the disapproval of pretty much all the people that matter in my life in order to learn who I am at the core. As painful as it has been, the peace I have in knowing who I am is priceless. I know that it will either enable me to give to my husband in ways I could never have imagined, or to be the kind of woman that the RIGHT kind of man is looking for if I am ever "on the market" again.
2. You can "stay well" in the relationship. This may seem like an impossible feat, but others have achieved success by allowing their strength to inspire/encourage/demand that their partner become healthier. They have stayed in their relationships, not out of FOG (fear, obligation, guilt), but out of a desire to help their pwBPD and/or provide for their children. They have found the strength to implement and reinforce he boundaries necessary to keep their pwBPD moving towards healthy interactions. I feel like option 2 requires some time in option 1, but that may just be my journey. Regardless, the objective in option 2 is to take an active role in helping your pwBPD become the kind of people that you will eventually be able to partner with in all areas of your life.
I'm not currently working on option 2, so I would recommend reading posts by those who are, like FormFlier. If your're in "Option 1 mode", even just temporarily, then please let us know what specific questions you have.
BeagleGirl