Not only is the depression real and very valid, but it changes, from manageable to unmanageable but the thing I think is important to remember, this is also a very valuable learning curve for a relationship - this kind of enforced separation will make you both stronger in ways that you cannot begin to fathom at this point in time and at the end of it you know there is a real prize.
There are many positive things to focus on these days that were very difficult when I was in this kind of situation for example, in '96, the nature of the internet has grown so much and is used so widely, e-mails, photo's and instant conversations when you can match the time difference and "he" pops up online! Text messaging, but best of all, much cheaper flights and certainly for Brits, more vacation times to make the trip (and you WILL believe me, I have been to NYC and back for one day!) and I know I am not the only one. MY telephone bills were sometimes the cost of plane tickets!
The most important thing to remember is to keep communicating, don't have any unrealistic expectations and keep talking, keep sharing, keep discussing, remain as 'open" as possible and remember that things can be very different in person to e-mail/text etc without it being intended that way.
Make LOTS of plans, keep dreaming and spend your time doing practical things for when you can be together one day, learn about the Immigration process, where you might work and live one day, so that you have a goal and as much of a cliche as I know it is, try hard to focus on the positives, instead of looking at it like your love is so far away, how about looking at like, aren't you lucky to have someone from another country who can offer you a different kind of relationship and without going into tooooo much detail, this is the kind of thing that keeps a relationship hot! Without putting too fine a point on it, absence makes more than ones heart grow fonder
I don't want this to detract from a depression that is real, so if you feel the sadness is spilling out into something unbearable that begins to affect your life, then do see someone professional and surround yourself with good friends who will support you during those times.
Good Luck to you both, such a new fresh relationship- it's the best place to be in girl!
Hugs
Sheril
~x~