Can disassociation last a lifetime?
I think that 'trauma' is basically dissociation for life, unless you seek intensive treatment.
I know that's not a direct answer to your question or situation, but with people with BPD... remember feelings equate facts. When you call up negative feelings, her disorder and dissociation as a coping mechanism make it easier for her to block you out of her head. This is done subconsciously of course, so no amount of talking will help here... I'm sorry to hear about your difficult story, and wish you strength and courage.