May I sue a person if knew they had herpes and gave it to me?

Technically the answer is yes, but this could be a very difficult case for you to pursue.  You would have to be able to prove that you contracted herpes from this one individual and there was no possibility that you contracted it anywhere else.  That can be almost impossible to show.  This is the type of virus that is impossible for you to show where and when you first came in contact with it.  As such, it would be hard to show that you contracted it from this one individual, if you have had more than one partner in your lifetime.  That being said, it would also be difficult to show the value of the damage you have suffered.  You could end up spending a significant amount of time and money pursuing this case and realizing very little in the way of compensation in return.