How much of it is actually the BPD?

[Ugh]

So after my ex-gf was diagnosed, I started to notice that there were situations that would make her stop her abusive behaviour. For an example, on my birthday she started up with typical abuse (don't exactly recall the reason. Could have been any number of things) and she was really ramping up into full-blown attack mode, but then my mom showed up to bring me a card, and my ex immediately stopped. Like a switch had been thrown. No crying, no screaming, no threats, no abuse. She was embarrassed. And that was enough to make her stop. But no amount of pleading or begging on my part would ever make her think twice. So doesn't that suggest that she knew what she was doing? If she was afraid of being caught in the act, she knows it was wrong! And it was clearly within her ability to stop... .just not for me. Only for her own sake. How do you chalk that up to an illness? They know the difference, they just don't care! At least that's the conclusion I drew. So how much of it is the illness, and how much of it is just being a jerk?

[2010]

So how much of it is the illness, and how much of it is just being a jerk?

Borderline is a thought disorder about intimacy. It is a persecution complex that is triggered by engulfment/abandonment issues. When a third party comes into the picture, the intimacy issues between the two partners are hidden in what's called the "detached protector" mode.  The detached protector is used to prevent the two child modes (angry child / abandoned child) from surfacing. Having a third switch, the "punitive parent" mode, causes the detached protector mode to shame the behavior and endlessly cycle back and forth between the two child states. Remember, this is a disorder and it is fueled by perceptions of persecution. Your part is one of the reasons that the two child states swing back and forth- toward and away from the intimacy triggers during attachment... .your Mother does not have that power. 

[blender]

Very interesting.  I never thought my ex's tears were real. She could turn on the water works, but she'd have to TELL me she was crying.  I always though it was phoney baloney. 

[pspap]

I can't disagree with 2010.     Once a 3rd person is put in the equation, the dynamics of triangulation (read definition) kick in and the balance changes.

Another thing that comes to mind from your description, Ugh, is that we tend to attribute a lot to the mental illness itself when, in fact, pwBPD repeatedly show that there are plenty of instances where they could react differently, yet repeatedly choose not to. It's hard to tell where the mental illness stops and where free will (or the true person behin the illness) begins. I can no longer separate the 2. I think that they are driven by an illness, but are often highly intelligent and excert control in the ways that they choose (otherwise they would have sought out help, wouldn't they?). Plus the manipulation tactics towards us as partners wouldn't work if they were all out there in the open for everyone to witness. Though, having said that, my exBPDbf did throw some pretty low blows at me in front of his parents in a passive-aggressive manner (aka in the name of humor - NOT).