@comeeliz,
First off, it really isn't you. It's him.
He's a jerk.
I think you need to get righteously angry. Not to the point of throwing stuff or marching down to where he works or anything like that. Just, be angry. He was at best discourteous, at worst, downright hurtful. You were together for not a very long amount of time, but it was longer than a week. And then he didn't even have the balls to say, "I'm sorry, but it's not working out." Even a lame breakup would have been preferable, amiright?
So go ahead and get angry. He was immature.
And once you've been angry for an hour or two, let it go.
He's not worth it.
Hold your head high. You did nothing wrong.