Welcome to the STD forum. Responding first to the title you chose for your question: HSV is not transmitted by mouth-nipple contact. The only possible exception is that if someone has an active outbreak of oral herpes, the other person could be at risk for catching HSV-1 of the nipple. Even this is very rare, although I had a patient like that about 30 years ago. But if any other sort of scenario is involved, there is no risk.
Now I have read the rest of your question. Guess what?
Presumably your partner meant she has genital herpes, not oral. If so, there was no risk whatsoever. People with genital herpes don't have the virus anywhere except the genital area. The only way you can get genital herpes from someone who has it is by putting your unprotected penis in her vagina or anus.
If your partner meant she has oral herpes, and if she had an outbreak (cold sore) at the time, then you could have caught oral herpes by kissing her. However, the chance of that is low. And anyway, about half of all adults have had HSV-1 in childhood (usually without knowing it); if that includes you, then you are now immune to HSV-1.
Final comment: Don't be so worried about herpes, even genital. Herpes is mostly a mild condition that should not be allowed to interfere with any potentially promising relationship. Even if that wasn't in the cards with this particular partner, you still overreacted in a big way. You likely owe her an apology and, if you're a mensch, dinner and flowers. Your appropriate reaction was to thank her for letting you know before things got further along -- i.e. before going on to actually have sex with her -- and certainly not to stop abruptly in a panic. Please do the right thing by her.
Best wishes-- HHH, MD
Yes, that's what I meant. Try dinner and flowers -- or at least flowers.
Dear Dr. HHH,
Thank you so very much. This has really calmed me down more than anything and re-inforced what my family doctor was saying earlier this morning.
I will apologize to her. I realized that this morning that I shouldn't have left so quickly and abruptly. In your last sentence, you said, "Please do right thing by her." I'm not trying to be technical but I do want to make sure I understand you completely, did you mean to write, "Please do the right thing with her?". I will apologize to her.
Thank you again.
Boeing777