Ouch...
You got yourself in a nice one!
First off, I'm against lying. I've had to deal with people who could do nothing but lie, so I try to make sure that I don't even tell white lies.
However, you didn't ask to be lectured about what's right and wrong, so I'll see what advice I can give you.
First off, gossip spreads like wild fire (which I am sure you are more than aware of). So half of what people are saying may not have even come from you. Which is a bonus of sorts that at least you didn't make everything that's been going around up.
However, the bad part is that you planted the seed and did nothing to stop the tree from growing. (Nice cliche, don't you think?)
The easiest way to deal with this situation is to tell people that you guys broke up. Something about distance or whatnot. Then it's up to you to come clean to those who you know deserve to know the truth.
The harder thing to do is to just let people know that you don't actually have a boyfriend in NY. You'll hate it and will probably undergo a lot of criticism, but you just have to remember that although it took you awhile, you did eventually come clean and can have a clear conscience.
Now here's the problem. No matter which you do, you're going to have to take into account the consequences.
If you go with situation A and tell people that you broke up, a couple of different things could happen. The most obvious being that there are going to be those people who figure it out and start talking about he probably wasn't real anyways. There are also those people who, when there is nothinig else to talk about, might ask you how your imaginary "Ex" is doing.
If you go with situation B it's going to take awhile for people to start to trust you again. You'll also have to deal with what they say about you because that is going to cause even more talk than what is currently going on. You'll also have to talk to the guy who originally asked you out because his feelings are going to be hurt.
I honestly don't know what to tell you. I know that it's said "Honesty is the Best Policy" and I agree with that, but I know that being in an environment where people aren't understanding doesn't exactly foster a desire to follow the best policy.
No matter what you ultimately decide to do, just remember this next time.
If you're not interested in a guy, tell him that while you appreciate his interest and are flattered, you don't feel more than friendship for him. Remember to take his feelings into account because it can be hard for some guys to gather up the courage to talk to someone they really like. (As I'm sure it is for you at times.
)
Wish I could help you out more babe, but that's all I got right now!
Good luck!
Ashley
Everyone else, I told that he'd dumped me for another girl. I guess i don't have the balls to fess up to sooooooo many people. But since I'm "hurting" from the breakup, no one else has mentioned him. Thanks for the advice guys! 
Sarah,this was hilarious.