It sounds like you are looking for closure. Very understandable.
You mention that this is your finacee. Do(Did) you have a date set? Ring? Announcement sent out? How close was(is) the wedding? Can you go through her relatives to settle financial obligations? They may (or may not) feel obligated to reimburse you for any deposits you put down for banquet halls or limo rentals. They may intervene regarding the ring. Tradition dictates that if the bride calls off the engagment she returns the ring. (If the groom calls it off girl keeps the ring and gifts for her trouble and heartbreak.
Has she done this before? Does she go through "phases" like this? Are you thinking this will "blow over"? If it does resolve itself with time, I would give lots of thought before making a lifetime commitment to this person. Either you are just not cut out for her or...she is not cut out for you. A finacee just does not "go cold" for no reason.