Since this happened several months ago, I’ve had plenty of time and emotional distance to think through what I could have done differently.
When possible, prepare ahead of time for the worst.
I was caught off guard. Before the meeting with my ex-landlady, I never considered the possibility that she might withhold part of my deposit.
If I had a do-over, I would have mentally prepared myself ahead of time for this possibility. The benefit of preparing for the worst is that I would have overestimated the amount she might withhold.
I still would have been upset about not getting my full deposit back, but much less so.