I'm angry at my girlfriend after she told me she has an emergency fund from before we started dating 3 years ago
What's the problem with having an emergency fund?
She should have told me before, we might have needed it.
You should respect her having her own emergency fund. You are not entitled to other peoples savings, especially from before you got together.
Well I had to find out on my own and it's inconvenient though.
Regardless, you're angry at her for an irrational reason. She made a wise choice to start an emergency fund and you have no right to be mad.