Ah, god. This struck an emotional chord within me.
Well.. I have a really bad history with guys, but..
Do you love him as well? Have you told him the way he makes you feel ?
You two can still keep n contact through a social networking site/ messenger/ email/ phone.
There's not much you can do to stop him from moving, but you can try and make the most out of the remaining time with him and savor those memories.
So hang out with him as much as possible and show him how much you care.. give him something he'll remember forever.