Streak31 - only you can decide whether or not to continue to chase a dream that may not come true (USNA) or embrace the opportunity you have been given(USAFA).
These are your two choices.
Here is some food for thought and questions that only you can answer:
Why did you apply to USAFA? If it was your backup then you have your back up. done deal. Have you visited USAFA? If not then can you?
You may end up liking it as much as you liked USNA.
What you must completely understand is that taking your FF scholarship to MMI means your spot in the class of 2014 at USAFA is yours to lose. This is your chance, your opportunity. You will be with a couple of dozen other young men and women through the year, will take AFROTC and be well prepared for Colorado Springs.
You can still apply to USNA if you want but would have to pay back the scholarship.
To get to an academy, your other choices - NROTC and Greystone are a gamble. You will be competing again for an appointment from a new pool of applicants. While some get in the second try, some also are rejected again. What will you do if you are rejected a second time?