Hey mrbo,
Sorry about your girl, its never easy.
My take on the situation is that it's over, over for now, over for later, you yourself are going to determine how much suffering you will face.
Seems as if your mind is asking a lot of questions about why she would do this, why she would say this. It really is quite simple, WHO KNOWS? You can sit and wonder, analyze thoughts and actions but overall it really does not matter why she said she what she did, she certainly is not going to sit with you and clarify what was/is going through her head.
Some posts say she said what she did to let you down easy, you feel as if she really did/does love you, I say both could be true but really, will you ever know?
So a much better more constructive thing to do would be to focus ALLLLL your energy on walking away (you'll need it my friend). You will hurt, you will want to call, you will wonder why she hasn't called, you will think she has moved on, you will think she lied during the relationship, all the wonderful things that accompany a break-up. However, you will move on, you will laugh someday, you will be able to think of her and not care, you will see the big picture. Like I said before, how soon you wish to see the latter is totally up to you.
Lastly, you mentioned that you do not want to seem weak in front of her. Pretending your not weak is still pretending, deep down you know you are in front of her. Point is that as crazy as it seems or sounds, not contacting her will be a reflection of how strong you really are and that is where you will get your self-confidence back and begin coming out of this with knowledge and self-worth. LEarn from it or you stand to lose a lot more than just a girl in the future.
All the best.