We are having to live under the same roof during the divorce.
Oof. That is rough.
I can see why it would be frustrating to have your stuff moved, even if it's not super meaningful to you. She's not respecting your space.
What about relocating the things you care about? This is pretty common legal advice. My L told me to move anything I cared about out of the house because those things tend to go "missing" or get destroyed during the divorce.
The part that is really unfair in all this is that your belongings are not valued at what it would cost to replace them, but what they are worth if you tried to sell them on Craig's list or whatnot.
Being BPD, she is going to really struggle with controlling her emotions and curbing her impulsive behaviors. Fortunately, being nonBPD, you can be more reflective with your emotions.
You are probably also better at being proactive rather than reactive (e.g. removing things you care about, for safe keeping).
It's pretty hard to have physical boundaries during divorce when you're both living together