I don't think this was egregious behavior on her part, and that you both might own a bit of what happened. I mean, after a few days with no reply, could you have called her in the event her computer was acting up or out of service?

When you see her on the 19th, I would just ask what happened on her end (had she gotten your email and forgot to respond or not checked her email at all for some reason) and then how to prevent something like that again and find out how she prefers to get communications. It may have changed. Like unaluna said, fewer people use email.

For me, it works best when I start off a conversation like that trying to get clarity first. As I learn more information, I can adjust my response (say, if I find they were just blowing me off).

After getting clarity and working out a way to communicate in the future, I would shift to talking about how not hearing back was triggering emotions related to what happened with your friend a couple months ago. Of course, you could lead with this, depending on what's most pressing. But doing it after the other leaves more time to talk about the emotions it brought up for you.