SmoothTalker I am in no way trying to discount you or anyone's terrible experiences with BPD women. I'm sure it can be hell.
The point I take issue with is when she starts acting up and the guy allows it to happen. As you say you are telling your friends tales of her insanity and they don't even believe it because it is so ridiculous.
The fact that you continue to expose yourself to this type of behaviour knowing full well it is wrong is where I don't understand. Would you accept this type of behaviour from any other person in your life? What about a guy friend? What about a real ugly girl?
What about if during your relationship with a BPD girl you start seeing a REALLY great and beautiful normal girl on the side? She's level headed, smart, fun, super sexy, sexual, and pretty much perfect in every way possible. What happens to your BPD addiction then???
If you choose the normal girl then were you really addicted to the BPD? If you choose the BPD then are you anything but weak?
So that is why I say that you guys need to take some responsibility for your BPD addictions. It seems to me that you are choosing sex over your own sanity.