J.S.
I wouldn't put the burden of the choice on your son of whether or not to call his dad or send him something. Tell him, "Jake, I'm going to take a picture of you holding your test! I'm so proud of you for getting an A!" After you take the picture, tell him, "Jake, your father will be so proud of you. Let's go to the computer now and send this to your dad. Think of a message for us to write."
I'm sorry things are in limbo with your husband right now. I would probably try to give him some encouragement... you know, reasons to come home. Tell him that you miss him. Tell him what you miss about him. Encourage him to come home for a weekend visit if he really does have to be away for work. Surely he gets time off here and there long enough for a visit with his family.
My point is not to make the phone calls and catching up all about your son or all about being serious, but to "date" on the phone or Skype or whatever... and make him wanted and needed and missed. If he can at least come home for visits then maybe it'll be easier to reconnect with each other.