HI goalie and thanks for using JustAnswer.com
I am so sorry to hear your situation. A couple of things that I know will not bring you comfort and you so dont want to hear, but adults do not change no matter how much you wish they would. I know full well that this is not the answer you want and because you care so much and so well for this person I know that you wish hard there is something you can do or say that would make them stand up and say Eureka! I see the wrong of my ways and I am going to change now!
I am so sorry to tell you that it is not going to happen no matter how much you wish.
Living with a bordlerline is heaven and hell. one day they are wonderful and then the next horrible. The drugs, the self mutilating, the drama is painful to watch and to live with. I have not known too many borderlines to lie but obviously there is much more here than bpd. Generally pathological lying is not a characteristic of bpd but who knows what is happening here.
I am sorry you had to endure this and you are quite the soldier to have done so much to try and help her. I wish I could offer you more comfort on this but the sad truth is that without a great deal of therapy people with bpd do not change and either you accept the constant roller coaster existence or you move on.
I am hoping you decide to move on. You deserve someone who is caring to you and does not make every day so difficult. If you decide to hang in and if your partner does decide she can tolerate therapy the best one I know of is DBT (Dialectial Behavioral Therapy) and it does work quite well, but it also takes some time of intensive treatment. The creator of this kind of therapy not only has BPD herself but was a friend and colleague of mine years ago. Dr. Marsha Linehan. If you google her and BPD you will find a wealth of resources.
I am just so sorry you have been through this experience.
You have all my very best and good luck to you.