Hi Doglover,
Welcome aboard! You have come to a great place for support and information.
The ups and downs of a pwBPD can be really frustrating. It is really hard to not take some of the things a pwBPD says personally. What kinds of things are you having trouble depersonalizing?
Learning about BPD can really help with that. Also, taking care of yourself first is another way to help depersonalizing the behavior. Seeing a therapist is a great start.
Here is an article to help get you started.
The Do's and Don'ts for a BP relationship Also, there are lessons provided on the right side of the page, that really do help.
Posting and sharing your story really does help.