I do not have personal experience with BPD but i wanted to plug what sounds like a good idea that you have. And i think that writing a book can be a particularly powerful kind of healing, especialy one based in experience. I think there are numerous examples of people writing memoirs about mental health topics, recent title called Excavation and well known author Lauren Slater come to mind. I think a book like yours would be educational not just for mental health professionals and clients, but it would also allow you to dig deeper into yourself and your life in ways that would likely be useful to you.