like everyone else is saying, i'd use some reverse psychology on her. she says she wants two weeks, you do the same thing too.. this gives you some control to help make you feel less helpless. I also do agree that it sounds like she may be doing some shopping around in this time to see if she can't find someone else that is better.... but if she doesnt... she is still making it so she has you. I'd be a little concerned about that being a possibility.
worst case scenario, even if she does remain with you -- I am a little worried that this may affect your relationship long term.... not that you would intentionally hold a grudge against her for this, but subconsciously.... i think you will.
good luck anyway!
Hunter S. Thompson once said "Buy the ticket, Take the ride."