PTSD is a very challenging situation for the person affected by it as well as his or her family and friends. The most important thing to realize is that PTSD is a medical condition that should be followed by a physician who can help connect your husband with the therapy and medication options that can help him manage his symptoms. If his military service is responsible for his symptoms, the military should be providing him with the support he needs. It is important that your husband see a physician for a complete evaluation so that his health needs can be properly addressed.
In fact, PTSD in military veterans has received greater attention in the past few years because of the conflicts in Iraq and Afghanistan, and there are more resources now than there were for veterans of earlier eras. Your sensitivity to his mood swings is important, but it may also be helpful for both of you to be able to interact with other people who understand what it is like to have experienced combat *or* to be the partner of someone who is dealing with those things. The Veterans' Administration (VA) hospital system will definitely have support groups and therapists
for your husband, but either the VA or local veteran's groups may have the same thing for partners of veterans. Talking with your husband and finding out what you can do to help him the most can also be very helpful.