I think if she were so upset that she really didn't want to be involved with you anymore, she would have said so by now. If she really wanted to break things off, it would be easier just to say so and get it over with.
Take her at her word and believe she just needs some time. You broke up with her on your terms. She needs to bring things back together on her terms. She's not going to bounce in and out of this relationship at your whim. Let her have control of this part and as hard as it is, just wait for her for awhile. She knows that you are sorry and that you still love her. If you haven't heard from her in a few days or a week, send her a card or flowers, as others have suggested, just to let her know that you're still thinking of her.
Time will be your greatest friend in this situation. Not much else will help. You just have to be there waiting when she and time come together.