I think people are getting confused. BP is bipolar. BPD is borderline personality disorder. Both are illnesses. The traits of BPD can sound like the traits of a "mean" person, but I don't think that being mean shows that one has BPD. It is so confusing sometimes. DBT (Dialectical Behavioral Therapy) can be effective for both disorders but was originally targeted for BPD. It is about examining the thoughts and emotions that you have automatically, and learning skills for controllong emotions and being more aware of thoughts so that the person doesn't have an outburst. There is time to think first. DBT also helps with self esteem issues by teaching assertivness rather than agressiveness in getting what you want. I found it helpful. It is hard work and some people do it more than once.

Anyhow BPD is just another disorder that has to be attacked with therapy and hard work.