Nobody is born with a personality disorder, though. If a person has borderline personality disorder, the roots of it will without fail be found in their childhood and how they were treated. What I also see in what the OP has written is the her mother is not being anymore rational than the OP is, which is a dead giveaway right off the bat. If I had a child and my child was threatening self-harm or suicide, I would have them committed, involuntarily if need be. It would not be a game, it would not matter if my child raged at me. However the OP's mother prefers to play a passive-aggressive game, prefers to invalidate her child by completely ignoring her child as punishment when the child says something unpleasant. I guarantee you that while the particular incident described above gives the mother at least some plausible deniability, that this pattern of invalidating the OP to the point that the OP flips out is not something that cropped out recently and out of the blue. What makes a situation like this extremely challenging for the person with BPD attempting to recover, is that they are still in the viper pit if they are still living with their caregiver(s). Focusing on and moving towards independence with sheer determination is the best bet for survival at this point, in my opinion.