Calm down dude, this is not something to worry about. First of all, her telling you, and the way she said it, is actually a good thing. She just wanted to let you know so you didn't suddenly get a surprise out of nowhere. I suggest that you read up a bit about herpes, because it's really not a big deal. I assume it was genital herpes? Lots of people assume that herpes means that the person in question sleeps around and isn't careful, which isn't the case. Like you said yourself, herpes very often has no symptoms, and tons of people live with it right now without knowing anything.

I'd say it's actually extremely admirable that she even told you lol, most people wouldn't disclose that. I have genital herpes myself. Got it from a girl i had been seeing for a while, and she was devasted when i told her i probably got it from her, since she had no idea she had the virus, and there was no way to find out. I also panicked a bit at first, but when i learned about how common it is i don't really care anymore. Have had it for around a year, never had any symptoms or outbreaks since the first one, all is good. Going around telling people i'm gonna have sex that i have herpes is a sure way to NOT get laid.