That would exactly be my answer. Get it out. Nothing is escalated, quite to the contrary: A clear boundary has been drawn, to end escalation right there. By the way, I would not yell but I would use bold face.
"Do not ever touch any of my stuff again. Never." Talk to her like you would to a child. If she doesn't look at you properly ask her to look at you because you have something important to say. When you are done, ask for confirmation that she understood properly. —
Peter A. Schneider 1 min ago