My wife, pwuBPD of 25 years can have a vengeful heart when crossed. For example, in the past she's posted things on social media (false things she believes were true) about an extended family member who crossed her. She never took it down.
Recently she had someone who was a very good friend but ended up telling her off something good. According to my pwuBPD the friend said awful awful things to her. I don't know if anyone's talked to my wife like that before. This happened like 4-6 months ago, maybe more. There's been no contact between them but my wife from time to time talks about how she wants to 'get her'. She's talked about how she could get her fired from her job . Most recently she asked me a question the other day that was quite disturbing to me - she asked if mail can be traced back to who it was sent from if it's sent from another area, like another town. She said she wanted to send threatening letters to this former friend. Something to scare her like "I'm watching you" or "I know where your son goes to school". Really messed up to me. She hasn't followed through with anything so right now it's just fantasizing but it's really messed up to me on so many levels.
Another example is a neighbor put something on their fence (a long privacy screen) that's visible from our side she hates. It isn't a shared fence, this is a foot off of our property, it's completely their fence. She's wanted to go over and have a confrontation with them about it. More frightening to me was she kept threatening to cut it down and pretend it wasn't her/us. She wanted me to help, participate or hide it to "support her". I see that as destruction of property, she says it's on our side of the fence which it's not, and it's not our property. I've had to go out a few times when she was out with scissors (and drunk) to stop her. I don't know if she would have followed through if I wasn't there to get her to stop but another messed up thing. Scares the hell out of me what could happen. And if she did what the hell do I do when the neighbors or cops show up?? And she gets mad at me for not being 'man enough' to go knock on their door to confront them and tell them off for putting that thing up...
My position is it's their property and they can do what they want. We don't really have a right to say anything but we can come up with another solution like plant some hedges or put something else up so we don't have to see it. If we plant a tree in our yard and my neighbor came over to tell me he hate's to look at our tree and how dare I put that ugly tree up I would think that would be pretty messed up. She didn't like that analogy...

.
Is this just the BPD or could it be NPD or something else?