[Kevin]

I'm in no way qualified to answer your questions. But here goes anyhow...

There is merit to each of those things.

If you value the relationship and ever have hope of it being repaired, you should obviously reply -- tell her how you feel though. It wouldn't hurt to open the door to serious conversation about how she basically cut you off. Let her know that friendship isn't something that occurs at the convenience of the parties involved. Just because you may have become an inconvenient friend was not a good enough reason for her to cease communications with you.

And there is merit to just saying f-it and moving on with your life. Sounds like y'all had something great, but it is either in the past, or it isn't -- the question of whether or not it's in the past I think is the most crucial part of your response.