There's no easy answer...
You have to be willing to have your whole sexual history discussed in front of a judge and jury. Then you have to prove several things..
1. That you got herpes from him and that it couldn't have possibly come from someone else. In other words, prove, in a court of law, that you didn't have it before you had sex with him and that there wasn't anyone else after him that you might have gotten it from.
2. You have to prove knowing intent on his part. He might argue that he didn't know he had it , or that he knew he had it, but his doctor told him that he wasn't contagious unless he was having an outbreak.
3. You have to prove that you didn't know he had it and still have consensual sex anyway.
The problem with cases like this, (No, I'm not a lawyer) is that these are often very difficult things to prove and you have to prove all of them. There's too much he said - she said.
One possible strategy you could use is to push for a settlement before it went to court, although, obviously you can't telegraph that to him. He has to think you're taking this all the way to a jury trial.
If it's revenge you're after, rather than the money, you might look into whether your state is one that treats knowingly infecting another person as a felony similar to assault and battery.
And honestly, the best revenge is simply success. This kind of guy is his own worst enemy and his bad karma will get him in the end anyway, without you having to do a thing. That worked for me with the woman that gave me herpes. I'm happy and with someone else and she's miserable and alone.