When I first started learning about BPD I came across a couple of websites dedicated to partners/family members of people with BPD. Alot of great information and help for those people.

http://www.bpdfamily.com/index.html

BDP Family also has a forum of other family members to share issues/strategies/successes etc much like we have here. It also has alot of resource material to help you understand what's going on with her and how you can best help/learn about what it is that she's going thru.

Other resources:
http://www.bpdcentral.com/blog/
http://outofthefog.net/Disorders/BPD.html
http://www.bpdrecovery.com/

Hope that helps.