You can do what warrior princess suggested or you can buy them a gift and wish them the best. Keep a straight face, don't get upset or even voice your hurt to them. It's best if you just act as if nothing is wrong sometimes.
Share your hurt with your husband. If you were to say anything to them it may just be like adding fuel to a fire.
Sometimes kids do not put a lot of thought into the things they do and how theses things would effect others. You do not invite someone especially your parents to a really important event in your life by leaving them a voicemail. Maybe they didn't want you guys there and that was the excuse they used.
Who knows? Try not to feel so hurt.
This really hurt you, you obviously know your son better but he acted in a way that indicates he was hurt about something. You need to establish what was on his heart. Talk this through with him and his girl friend and be ready to swallow pride and forgive them.As a parent who loves their son I would offer to have a celebration at my house and give them a gift then to show you surport them and love them.
Sometimes children are soo immature , only when they have their own children will they understand the error of their ways. You need to be open but not accusing> your son was wrong only he does not see it yet.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.