I had to sneak in a comment because if anybody knows about travelling hubbies it's me.
Hubs is in the navy and has been gone about 19 months out of the past 36. It does kind of suck, but at least it's only 4 months, and you'll still get to see him a bit in there.
But... a few suggestions that might help. Make time to say good morning and good night every night-- whether it needs to be a text in the a.m. and a call at night or whatever. Even if it's five minutes-- that connection is super important. Figure out how to skype and set up a schedule. Hubs and I were doing once a week, but you can do more often than that if you have the time between the two of you. That way you can have a skype "date".
And last, make fun plans for when he's home so that you have that to look forward to.
And for you-- make sure you're taking time to take care of yourself. Being home with the kids alone can make it easy to overdo and end up sick or in pain-- even without the chronic pain you have. Remember, if you are down you can't be there for them as well, so if you need to do a little less than you think you should at times, DO IT!