Hold on, buddy. There's hope for you yet.
Your first course of action should be to call up your ex-girlfriend and give her the ass-chewing of a lifetime. If you've already done this, do it again. It'll make you feel better, and she deserves it. She was either completely bitchy for hiding the truth from you, or completely stupid for not paying attention to her body and knowing that she had the disease. And now you're paying the price. So go ahead and make her pay a little, too.
Now that you've got that out of your system, move on with your life. I'm guessing you've already been to a doctor and been properly diagnosed. If not, do it NOW. Self-diagnosing can be a dangerous game, so it's best to let the pros handle this. Plus, docs can give you meds to suppress breakouts, which is a huge plus. No breakouts = no pain, no suffering, no strange-looking wounds (most people prefer non-scabby dicks), and much more success getting laid.
As for sex, what's stopping you? Go out and get some! Just do two things:
First, you gotta tell your partner that you've got the big H. I realize there is some stigma that goes along with this, but be brave! This will only turn off the shallow and uneducated. And we all know that it'll be their loss, you stud - herpes has no effect on your ability to perform, so you can go all night long. If you're too chicken to be honest, and you pass herpes on... there's nothing I can do. But that would make you an evil, rotten person, and no better than your ex.
Second, you gotta use a condom. If you don't want to do this to protect the person you're with, do it to protect yourself. What if you're sleeping with someone who has a different STD? You think one is bad, imagine dealing with two. Your chances of getting laid will drop by about 90%, based on sheer stupidity. One is forgivable. Two is not.
And remember, there's more to good sex than just intercourse. So take advantage of the times when you do have an outbreak (when you're very contagious and should definetly not be having intercourse) to get really good at oral. It's a skill that goes a long, long way - hell, some people even prefer oral to intercourse. If you've got this in your bag of tricks, you're set for life.
And for those days when you're feeling really down about yourself, just think about this: more than 45 MILLION people in the U.S. have herpes. That's almost 1 in 5 Americans who are just as unlucky as you are. You're not alone buddy. Hell, you even have a hotline - The CDC National STD Hotline: 1.800.227.8922, so if you've got questions and you don't wanna call your doc, give them a ring. They know what's up.