The first thing that I want to say is that every situation is different and I dont want to get your hopes up to be let down one more time. However, I believe from what you have posted that I may be able to relate to your ex-girlfriends situation.
Truth be told she may just be worried about losing a friend in whom she trusts so much of herself when that is all she wants.
The other possibility is that after such a long relationship she is unsure if she still feels the same, so she wants to explore. She wants to kind of keep you on a back burner so to speak... this is how i felt throughout a five year relationship that ended w my ex girlfriend 8 months ago. Now, unfortunately, we cant get back together and its my fault (A long story why). However, I think the biggest downfall was that i didnt think i could ever lose her. Now I would marry her if we could get back together. The point is she may think she can always have you yet still look over her shoulder...
My advice would be to tell her if you are breaking up than you need to be apart for a while... force her to leave you alone for a while... a couple months even. This will give both of you time to think without eachother there to provide influence. Keep yourself busy during this time period so you are not depressed and resist the urge to contact her and if she contacts you just say you are not ready to talk yet. (THIS TAKES A LOT OF WILLPOWER).
The end result is after a couple months you will both better know how you feel. Now when you talk to her if she really loves you she will be more than ever ready to get back together... the downfall is that she may realize its really over... truth is if it is over than it would have endded anyway... maybe later, but it would hurt that much more.
All I can say that I was in your ex-Gf's position and after a couple months apart I was begging my Ex to take me back... Too bad for me we had other complications in between.
Wether or not you want to try this plan out is your decision, you know your situation better than some stranger on the internet.
So hope for the best, but be more than prepared for the worst.
Good Luck