So if you had antibody to HSV 1 at your October test, then the outbreak that you describe could not be your first infection because you already had antibody. You were infected at some point prior to October. I don’t know if they symptoms that you describe about other possible outbreaks were herpes or not, just know that you had HSV 1 prior to the test in October
As for partner B, he may well have been exposed to your HSV 1 infection, yes, but if he has any history of cold sores or tests positive for HSV 1, then he is not at risk from your HSV 1 infection.
I certainly have no idea where your doctor came up with that statistic of 1/10,000. That seems off to me, but since we have no statistic about HSV 1 transmission, I cannot give you an alternative number.