The reason why I wanted her back after the breakup was mostly physical - her beauty, the sex, etc, and the initial feelings of idealization which were long gone. She had turned into a cold callous person. She had a very rough upbringing and was sexually abused at a young age. I realize that she had a child like emotional state and the relationship could never work because it was a co-dependent relationship.
pipsi,
Welcome to BPD Family. From what you have described, it would seem you want to have a better understanding of what happened to you, so you can get some closure. Having a medical background, you will likely want to look up the term "love bombing" which has often been called "sex bombing" even though these are not medical terms, it will describe the 2nd symptom of BPD in the DSM 5 more commonly known as the "narcissistic abuse cycle" which is common to most of the Cluster "B" PD's.
When a woman is hypersexual, it is usually for one or both of two reasons. One is to prevent being 'abandoned' the first symptom of BPD in the DSM 5, the other is to do emotional/psychological 'self-harm' to relive the sexual abuse they had as a child - a very unsettling thought to say the least.
You mentioned that this relationship was a codependent one, and you should not be in it, and that takes strength to recognize. You also are self-aware of your narcissistic traits and are actively working on that, that too is a good thing, as most people who are PDed are not self-aware.
Since you are on the 'bettering' board - are you interested in reviving this relationship? If so, why?
Be aware, many, not all, will 'recycle' (a.k.a. h-o-o-v-e-r) after a period of time. If and when she does this, you need to decide what is best for you, whatever, that might look like.
All of this can be quite stressful, so be sure to do self-care whatever that might look like for you.
Take care, with self-care.
SD