My husband is not in the military but has suffered with kidney disease for most of his life. 4 years ago he went into full-blown renal failure, and his behavior was very similar to your husband's. It has been a HUGE battle to remain patient and loving when my husband is yelling, rude, and just checks out all the time. For him he works on his computer constantly, not even answering questions when I'm standing right next to him.
I don't have a perfect solution. What has kept me going is remembering that this is not the man I married, his personality has changed. He needs as much love and support as I can give him, and since I'm in the thick of it with him, I'm the best one to really support him. I also take quiet time for myself every single day (often only 20 minutes), so I can recoup from the tense environment. We have two small children, so our house is active.
The other thing was told my husband straight out, I don't appreciate your behavior. I know you don't feel well, but I don't appreciate you taking it out on me. That seemed to help him snap out of it some of the times.
In addition 5 years ago I almost died from a ruptured aneurysm. That experience left me with severe PTSD. I was petrified to exercise or move too much lest something else inside me explode. I also became super anxious that something tragic would happen to my kids. Between my husband's behavior and my inner anxiety I was a nervous wreck all the time.
I did several different therapies to get to the other side of it. Last year I did Lifespan Integration therapy. I would really urge you to look it up and see if there is somebody in your area who can do it. It's a very simple therapy, like a guided meditation, and it has profound results. I asked my therapist if this would work with any kind of PTSD, and he said he was working with the local veteran's groups to set up a program for veterans. He said this would be very, very helpful for them. I only went 10 sessions and it resolved the intense anxiety I was having. I don't take any more medication, and I rarely have any anxiety anymore.
Blessings to you, your husband and your family.
B.