It's a bad friend thing to read and ignore messages to make plans, right?  

My BFF has been ignoring messages to make plans for a couple hours from now for the past few days.  It's marked as read.  She can't even bother with a "nah" or "idk" and it's really bothering me.  I've really been thinking about what I could have done to piss her off, but the only thing I can possibly imagine is me hanging out with a friend she doesn't like.  Not that she'll tell that friend; she just avoids them.  Has been, for years.  They think they're still her friend!  

The only reason she even dislikes said friend is because they've treated ME poorly years ago, and I'm approaching being friends with them cautiously.  My BFF and I were very close with a third friend who just cut off all contact with us (and like 15 other people) one day and never explained why or anything, which honestly took years for me to be a little okay with it, so I'd hope she'd get how that feels, but I can't help but worry that she's doing the same thing to me.  Meanwhile, she's reblogging things about 'I honestly can't stand you' and stuff, and I'm like "I REALLY hope that's not about me" internally.  

But I don't voice anything to her because I have always worried that if I do, she'll drop me for good.  We both have BPD (I'm positive she doesn't use reddit or I wouldn't post any of this) and usually it's fine, but sometimes she just gets really mad at people for tiny things and holds onto it and it seems like if I don't back her 100%, I'm out.  There are periods where she's just a bad friend (I'd go into detail, but it doesn't matter for this post, so why be mean?).  I'm sure that it's partially true and partially me just worrying too much, but I don't have a lot of friends.  I don't want to lose the ones I have.

Is she doing something socially inappropriate?  Regardless of the first answer, should I confront her, or just wait it out?