When I was a teen, my t at the time pinpointed this as the diagnosis I would have were I not a teen. Since I was a teen, he said that I had traits of BPD, and that I may always have some traits of it (BPD is not a diagnosis they typically give to teens, assuming they will outgrow some of the behaviors, and maybe it is just teenage angst and rebellion).

I read every book I could find on BPD. I tended to see myself a lot in the BPD diagnosis (but it's interesting, because a hallmark of BPD is feeling like you don't have a solid sense of an identity - like you are a "candle in the wind" or a chameleon taking on the emotions and identities of whoever you are around at the time, trying them on and seeing what fits... So in a way, the BPD diagnosis gave me an identity, if that makes sense. I kind of accepted it - even though it was not an official diagnosis).

Some good books I read about it:
Lost in the Mirror - Richard Moskovitz
Get Me Out of Here - Rachel Reiland
The Buddha and the Borderline - Kiera Van Gelder
Loud Inside the House of Myself - Stacy Pershall

I didn't get much out of the stop walking on eggshells books. Don't know why. Nor the I Hate You Don't Leave Me one - although the concept is quite familiar.

Here is a great blog about BPD that I stumbled upon last night:
Beyond the Borderline Personality - Beyond the Borderline Personality... There's some really great educational stuff on there, and I relate to a lot of it or at least learn from it.

In all of that reading, I have heard it described by Marsha Linehan (the pioneer and founder of the therapy specifically designed to treat BPD, which is DBT - Dialectical Behavioral Therapy - which you probably already know all this, just in case someone else hasn't heard of it though, who also came out as having BPD herself) as feeling like an emotional third degree burn victim. This makes sense to me. As such, a person with BPD will be extremely sensitive to the emotions of others around them. There was even a study where they took 20 people with BPD, 20 people with no mental illness, showed them each videos of faces where the faces changed from neutral to showing an emotion, and those with BPD identified the change quicker on the whole, than those who did not have BPD. One reason for this might be that a person with BPD is always scanning the emotions of those around them and looking for signs that a person is going to abandon them (another hallmark of BPD - the fear of being abandoned, rational or not). So you take a person with heightened emotional processing and they will read into a facial expression, or even a comment a loved one makes - and read into it negatively - thinking, oh this person is surely going to leave me now. Then because of the fear and helplessness, they will have a reaction. Maybe some of the classic acting out behaviors - risky behaviors - or maybe even fight, and go into a rage due to the extreme feelings of helplessness and feelings like the person is going to abandon them anyways, and there isn't anything they can do about it, so to have some feelings of control, they might help this happen and push a lover out the door, or a relationship over the edge, to where this manifests itself and the person with BPD really does become abandoned. Then sets in the negative emotions towards self - suicidal feelings, or the chronic feelings of emptiness (another hallmark of BPD).

And then on top of all of that - the stress related paranoia, or at an extreme, stress related psychosis (or dissociation) even... probably related to early trauma(s).

Linehan and others say that a person with BPD, or some the BPD symptoms, grew up in an environment that was somehow invalidating to them and their existence. A large part of treatment- (along with learning basic emotional regulation and distress tolerance skills that for one reason or another, a person with BPD just never learned - maybe because the parent had a mental illness, or had substance use, or was absent - and they did not have these skills either so they could not teach them) is learning how to self-validate - one's self and one's experience and one's existence. This self validation is important, because a person with BPD has been looking outside themselves for this all the time, and hence always living in fear of abandonment. Because abandonment basically feels like death to the person with BPD - if the person they have been relying on for validation or even at the extreme, proof of their own existence.

Just some thoughts, take them or leave them..