I am terribly sorry that this happened to you.
You could sue her but unless she has substantial assets you might not be able to find a lawyer to do so on a contingent fee basis and might have to pay for the representation. Then, even if you win the suit, you would have to wait until she had some assets to collect from.
It also might be a difficult case to prove. Unless you had tested negative for herpes before you started dating this woman or the strain of herpes that you now have is the same strain she has, you may not be able to prove that she gave you herpes. If I understand the medicine correctly, it's possible for one to have had herpes without knowing it and for a dormant herpes to start producing symptoms years later.
If you do sue for intentional infliction of emotional distress, remember that the case is public record and, since you will have to prove that you got it from her, your entire sexual history will be explored. You could also talk to the police department for the town where the sex act occurred to see if they would prosecute her for assault and battery. Again, such a criminal proceeding would be public. If the state won the case against her, or if she pled guilty, she could be ordered to pay you restitution.
I just noticed that you listed the practice area as divorce. I will change it to personal injury when I am finished answering. You may want to use the Find a Lawyer button to look for a personal injury lawyer in or near Wakefield to discuss your case in private.
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I am sorry for your terrible situation. The idea that there is someone that could do this intentionally is actionable. Causation will be difficult to prove unless both of you were tested in the time leading up to the sexual contact. I agree with my colleague that unless she has significant assets, it will be very difficult to find a lawyer to take the case.