Hi heartofglass,
I'm so sorry for the loss of your dad, the anniversary of his death sounds like it is triggering a fresh round of grief. I lost my dad years ago and still miss him everyday. Grieving a loss happens in our own time in our own way. The 5 stages of grief... .Denial, Anger, Bargaining, Depression, and Acceptance do not come in any particular order and you may bounce around several different stages at once.
I also can see why you would be angry with your mom, it probably feels like your dad didn't matter at all to her and as his daughter that is very hurtful.
She has a mental illness that isn't rational and no matter how much you try to make it rational it just isn't. Your dad's death is actually what someone with BPD fears most... .being abandoned. Death is the ultimate abandonment. She is now scrambling to fill the void left by your dad's death. Does that make her apparent disregard for your dad okay? Of course not it is completely insensitive to your feelings and those that loved your dad. But it can be completely logical for someone with BPD.
I arrived on this website a very angry lady too. My SO (significant other) has an uBPDxw (undiagnosed BPD ex-wife) that was doing amazingly hurtful things to him and their 2 daughters. It has helped me to really understand what BPD is all about (I read a lot of books on the subject) and then coming here helped with further developing my knowledge with peoples real life, real time situations. I also learned tools and techniques that helped me handle our situation better and eventually I was able to get to "Radical Acceptance" regarding the ex. She is who she is and it is not in my power to change her. What I can do is manage the ways in which I interact with her or not.
You may not be at a place of radical acceptance yet but below is a link to more on that topic... .
https://bpdfamily.com/message_board/index.php?topic=89910.0One thing that helped me was coming here and talking to other's that "get it" and just being able to vent and get other's perspectives could help me cool off or look at things from another angle.
I hope I've helped some.
Take Care,
Panda39