Having Herpes shouldn't prevent you from being in the nursing field. Nurses wear gloves when dealing with bodily fluids. Unless you have a Herpes outbreak on your hands or in some place that's not normal and the patient would come into contact with the secretions then your safe. I'm going to assume you won't be kissing or sharing bodily fluids with your patients.
Herpes comes in the form of type 1 which is most likely the one people get on their lips, or face, and type 2 which is most likely on the genitals. Keep in mind you can get either type pretty much anywhere you have membranes. It is possible to get Herpes in your nose, an open wound, your rectum, mouth, and occasionally it will follow the nerve patterns on your body. This means you could get an outbreak on your abdomen, leg, thigh or anyplace the nerves run.
Most people with Herpes can do any profession they wish. You just need to be aware of your symptoms and when your shedding the virus. Obviously if you have an outbreak you couldn't touch it and then touch any patient without properly sanitizing your hands. Properly sanitizing your hands is normal procedure for prevention of diseases in the nursing profession. There are several medications available that will lessen and reduce outbreaks if you have them frequently.
Talk to your doctor about your concerns and he/she can tell you when and where you need to be concerned. Good luck and don't let Herpes stand in the way of your dreams.