Hello dredgie, welcome to the son/daughter board.
You say that you and your daughter have developed a pattern of interacting that is very upsetting to you and which you don’t want to participate in anymore, that’s a very wise decision to make. Yes, it is emotionally exhausting trying to have a relationship when one minute it’s on and the next it’s off. Not to mention the abusive texts as well, I can definitely see that it’s a roller coaster that you want to get off.
If you are not already doing so, I would suggest learning as much as you can about BPD so that you can get a good understanding of what’s going on. There are also TOOLS and LESSONS to be found on the right

You will find there are certain skills that can be learned that can help with communication.
Reading other members posts and asking questions are both good ways of picking up vital tips too.
Look forward to reading more from you x