Like Chris said, having other people, and I'd add, things to do (help you take your mind off it, concentrate on something else) should at least make you not feel like crap. It'll probably still be pretty hard, but not as bad as it would without.
I went through the whole miserable process for about a year, and it was awful, but I didn't have anyone I trusted enough to talk to about the subject (certainly didn't know about cblf), or any friends, for that matter.

It's great that you want to cherish every moment you have with him, but you may run the risk of thinking of nothing but, once you're away. I became obsessed with my YF when I moved...I had nothing so good ever happen to me in my life! and I didn't want anything but to be with him. You may want to put things in perspective, explore the nature of the relationship, etc, before you go away. I'm sorry if I sound a bit bossy, but as I'm writing this my heart completely aches for you, that you have to go through this, and I hope that it won't absolutely ruin a couple years of your life as it did mine, cause i didn't know how to handle it.

You have 3 months. enjoy the heck out of them! and try to move on (with life, that is. I don't mean "forget him"). Even if you still call him, chat, text, etc, it probably won't be the same, however much you may want it to.

I wish I could be of more comfort, but IMO you have to have a battle plan to deal with this, or it could really haunt you (you may have a completely different reaction, I know. I just REALLY X 10 don't want you to go through what I did.)