Keeping her out of the vacation plans will not solve the fundamental issue. Sure, she won't be able to manipulate you into not going, but if this really is BPD, then the vacation problem is unlikely to be the only issue. It affects all aspects of your life, not just vacation plans.

In the end, the only thing that might make a real difference is for her to get professional help, and it will be a long and difficult process. She is the only person who can change her behavior. The fact that she is diagnosed is very positive, as it means that presumably she at least acknowledges her issues, which puts her in a position to work on them. That's a great first step, and one which not everyone with BPD is capable of.