Dear Young and Confused,
Either break up or quit your job.
It may be too late. You are in a relationship that is the classic sexual harassment situation. The age difference is significant (plus you are underage), but the biggest issue, in my opinion, is that he is your boss. I have no problem with co-workers dating or even students dating teachers (once the class is over), but your boss is off limits.
Power and Inequality
Why? The very nature of your relationship is based on power in the workplace. He controls your livelihood. Do you really want that inequality of power in your relationship with a boyfriend? What if things don't work out the way he wants? Is he in a position where he could fire you for this, or worse, make you do things you don't want to do? It's icky, and it's dangerous.
I think you've gotten yourself into a very sticky situation. Even if both of you could break up and still work together, the damage is really done. I think that all you can do is either get transferred within your company or leave your job.
He Likes the Power
Get out from under his power and then see what's left of the relationship. You may find that you are not attracted to someone who isn't your boss. If that's true, I would get some psychological help -- it's not healthy. If he loses interest it means that he is was dating you for the wrong reasons -- he likes having the upper hand.