Hugs to you.
I don't have any personal experience, but I can imagine that this is a difficult decision that only you will be able to make.
I don't know if this is helpful or not, but my approach for making the decision would be to read up and study the risks associated with having a vaginal birth w/ genetal herpes and compairing them to the risks associated with a C section. If the chances are low that you could pass on any sort of infection to your child with a vaginal birth - even with an outbreak, I would probably try for a vaginal birth. (That's just my perspective, even though I've had 3 C sections!)
Is the risk really different if you have an outbreak vs. if you don't? If so, maybe your doctor will let you go into labor naturally and if you have an outbreak at that time opt for a C section?
Good luck with your decision! Maybe someone will pop up here who has first hand experience!