Rapunzel just did a good post on another thread explaining Borderline:

http://forums.psychcentral.com/showthread.php?t=101568

And don't feel bad for not knowing about it - I hadn't ever heard of Borderline until some online friends on a parenting website told me I was a Borderline 3 years ago. They were dead on. The first time I read the symptoms I knew it was me, exactly. But I had never heard of it until I was 25.