Mines a Marine.
My advice to you is this:
1) Stay Busy! even if you dont feel like it, get out. Get a new hobby, hang out with friends, clean, pick up a sport...or two, travel, whatever you need to do to stay sane.
2) Dont let your life revolve around him completely. You have to live your own life too.
3)Write often. It lets you tell him everything thats going on and makes you feel a little more at ease as welll as comforts him.
4) Find things that help you cope and de stress. Bubble baths, music, singing at the top of your lungs in your car, crying every once in a while is not a bad thing, treat yourself to a pedicure, whatever it is just keep yourself as happy and healthy as possible.
I know its tough right now, but this really is a small taste of what the future will be like. Its rough, but possible if you love him. Just dont let your life revolve only around him and keep yourself sane. Dont forget to be HAPPY! I have to remind myself of that sometimes.
Good luck hun, I really hope everything works out.