If I am reading between the lines of your post correctly --
You contracted HSV from your ex and shortly after this happened he's telling you that he has got HSV orally from you because he's suddenly having cold sores.
Okay, it's unlikely (very unlikely) that that is how things went down.
First. It's very difficult for people who have HSV2 to contract HSV1 -- it has something to do with how the antibodies are structured. However, it's pretty easy for people with HSV1 to still catch HSV2 (the antibodies for HSV1 don't do a very good job at fending off HSV2 unfortunately).
Assuming you are correct about catching the virus from him (as in no way it was anybody else) I'm willing to bet that he had HSV1 orally already. Most people with oral HSV1 contract it in childhood (numbers are dropping as people are grasping that it is contagious, but it's still pretty common amongst kids) from a relative who doesn't realize their cold sore is contagious.
In young people (i.e. the under 25 crowd) genital HSV1 is very common because oral sex is very common. If you come back positive for HSV1 I'd be willing to lay money that your ex gave it to you through oral sex without even realizing he had oral HSV1 (cold sores).
If you come back positive for HSV2, well odds are he had both types without realizing it (not an uncommon occurrence believe it or not).
Lots of people go years without oral outbreaks and don't even realize they have oral HSV. I'm guessing he suddenly had an oral OB and figured you must be the cause of it without bothering to find anything more out about the virus.
You definitely need to find out what type(s) you have (Ideally your original outbreak was cultured, but if not get yourself a type specific blood test once you reach the 12 week mark from when you first developed symptoms).
At the end of the day you probably wound up with this because, even if he had got tested for most STDs, he probably never had a test that looked for herpes (standard tests for STIs do not include HSV screening). Odds are until you developed symptoms you were never tested for it either.
Onto the more cheerful side of things:
YOUR LIFE IS NOT OVER. This is a bump and you will feel better physically and emotionally. It's a bit of a mind blower to find yourself wrapping your mind around all this, but the shock will pass and you can come to realize that what you have on your hands is just a very common virus that will not prevent you from having relationships, a career, kids, marriage, mind blowing sex, etc. if you keep things in perspective.
THERE ARE LOTS OF PEOPLE OUT THERE WHO WILL GRASP THAT HERPES IS JUST A VIRUS AND NOT A REASON TO REJECT SOMEONE. Not saying that's everyone, but we have lots of success stories around here that demonstrate that herpes is far from being a deal breaker. I contracted herpes when I was a tad older than you (I was in my early 30s), but I was single at the time and it still felt for a little while like the world had ended for me. I have now been married to the same man for 10 years and we have 2 wonderful children and my husband and I have a very physical relationship.
THE MOST IMPORTANT PIECE OF ADVICE any of us can give you when it comes to dating with herpes is to make sure to tell perspective partners about you having herpes before you ever get intimate. This is less about the actual risks involved versus establishing trust up front with prospective partners. It doesn't have to be a big confessional type conversation, but before the clothes come off you should sit them down and give them the news. I did this as soon as the second date and late as 3 months into things (or never when it came to guys I never got intimate with)--but it was always before things got naughty. I never got rejected over my herpes status. .
Keep on hanging in there. Things do get easier.
Hoe eet jy 'n olifant? Bietjie vir bietjie.
(Translation from Afrikans: How do you eat an elephant? Bit by bit.)