Boil is my guess too, but if you have concerns then please attend your doctor.
If you have been having sex with partner(s) whose STD status you do not know then please consider an STD panel that includes at least HIV, Hep A/B/C, gon, syph, chlam, trich, HSV 1/2.
I remember trying to look into this some time ago but best I could come up with was that the chance was say in the range of 1-10% for the sexual episode. Obviously the nature of the outbreak, its positioning etc. all plays a role.
You suggest this is HSV-2 with a diagnosis over 12 years ago? Have you checked the type with a blood test? May be a chance it is HSV-1 that your husband may already have for example.
Agree that antivirals have no preventative properties, only benefit is taking the edge of the impact of an initial infection if this occurs (which as mentioned is still the realms of quite unlikely).
Having HSV-1 does not provide any protection from HSV-2 so the figures show. Interestingly the other way around there is almost complete immunity, that is, people with an established HSV-2 infection are much less likely to be infected with HSV-1.
You are more at risk when there is an outbreak so it is possible but as the other person said he may already have it anyway because if you have been in a relationship with him and having sex over a frequent period it is more likely that he would have it according to the experts. And if he takes an antiviral straight away it does not stop him from getting it I'm not sure what the above person was referring to there