@PFChange: Thanks for the link! I read it through and wonder: can she have both PD's? There are many things with NPD that fit the bill, but BPD seems to have the edge.
Yes. BPD is often comorbid with other Cluster B disorders (NPD, AsPD, HPD). There are a lot of overlapping traits and behaviors as well.
My next question is: should I reply, or not?
To me it sounds like you already answered that question. Check out what you wrote below...I put it in bold.
Of course we have restricted all wedding photos, much to their disappointment. Heck, since they didn't come, they've lost the privilege to see any of them and I've decided that no contact is best, complete and final.
If you mean that, there's no reason to reply. However, if you think you want to explicitly say, "Stop contacting me," that's all you need to say. You don't need to respond to anything in her letter. I found the info in this link helpful: How to stop circular arguments
And for your reference, here is the one on BIFF: TOOLS: Responding to hostile email