Is there anything to stop the spread of genital herpes after finding out that the partner had fever blisters?

Confused: Fever blisters are usually referred to herpes labialis (cold sores, caused by hsv, type 1 virus), which is not genital herpes (caused by hsv, type 2 virus). Occasionally HSV 1 virus may be transferred during oral sex to the genitals of the partner of the infected individual, but this is not very common. The best way to prevent spread is to avoid direct contact with the infected body part.

Not much to do: Fever blisters normally means oral herpes due to HSV1. If your partner had an oral herpes outbreak, you might be at risk for genital HSV1 if he performed oral sex on you. If you mean he had a genital herpes outbreak, you also could be at risk, probably for HSV2. Once exposed, there is nothing that can prevent infection. But most exposures result in transmission. Here's hoping you luck out!