Don’t know how to feel

A trip to see you would take a lot of holiday days. Maybe they are only going camping for a couple of days so not using holiday.
In the case of sons the in-laws always get priority it is just the way it is I am afraid.

I can understand your disappointment. In your mind Christmas was sorted and you were looking forward to spending it with them all.

Wouldn’t spend time speculating the whys or who said whats. Like you I doubt son just forgot but you don’t want to put him on the spot.

Do you speak to DIL? Perhaps you could arrange a date in January with them both so you know there is no confusion or double booking? I always think it’s “flat” after New Year so it will be something to look forward to.

I can now understand the true source of your disappointment.
So the issue is that you haven't seen your gc and family in 15 months and only talked to gc once in 15 months (the Skype call for your birthday I assume)
How often do you communicate with your son and family, especially during those 15 months?

You wrote you always travel to them.
When was the last time you and your dh went to see them?
If you haven't seen them in 15 months, is it safe to say you visited them September 2017?

How much distance is there between you? How long does it take by car or it has to be by plane?
How old is your gc?

It is not unusual to have parents travel to see families with kids as it is easier to pack or/and pay for plane tickets for 2 people vs 3 or 4 or 5, etc.

If it is a well established pattern that you always spend Christmas with your son at his place for years, yes, your son dropped the ball.

If visiting them for Christmas is sporadic and once in a blue moon, I can see how "we visit you for Christmas and I don't talk about it anymore for weeks" is seen as non committal for your son. Your dh dropped the ball.
What did your dh expect, just say in December "hey son, we will be there in 2 weeks and leave by January 2nd" or for you to jump and arrange the details? What was his plan to organize this trip?

I would work on the relationship with your son and his family all year long.
It is not realistic to put all the hopes in Christmas and have a hallmark meaningless perfect family visit.

Hi Kartush, it seems to me there has been a bit of a misunderstanding between your husband and son.
I'm surprised that when your husband suggested the visit that your Son didn't mention, "running that by" his wife, to see if any other plans were in the pipeline.
If I ever invite either my son or daughter, I can guarantee that they will say that they will have to check arrangements with their partner first.
I think this is all that has happened, your Son has agreed for you to visit without checking with his wife if she had any plans.
Make firm arrangements and dates for January and you have that to look forward to.

Isn’t it horrible when things we have built up in our minds get changed or haven’t been set in the stone we thought they were I can certainly understand your disappointment and empathise with you but as others have said can you visit in January it’s not too long after to wait and you can have a ‘second’ celebration with the grandkids
I hope you can get over your sadness and enjoy Christmas anyway

Tedlbar ....speaking directly with my daughter in law is sometimes problematic as she doesn’t always answer her phone or reply to messages and she usually leaves things to do with us to our son

@Hithere. Our last visit was in september 2018. I try to phone, text, message as often as I can but probably only manage to speak to someone once in a blue moon, mostly my son. My son did message his father for Father’s Day
They live 2500ks from us Which is about 18 hours drive. It is a three day drive for us as I do not drive but two days for them as they can share the driving. Fly/drive could be done in one day but would have to hire a car
My grandchildren are 10 and 8
I honestly do not believe my husband dropped the ball, he did what we always do when we go to visit them, ring first and find out if it is ok to come, then if it is ok we sort our end to get specific dates then ring back and check the dates with them. It has always worked in the past.

Awww Kartrush I always find it sad when DIL's dont regard their in-laws as part of their family and leave it to their spouses to deal with also knowing that wives generally have the upperhand when it comes to 'arrangements' .

I think I agree that neither you nor your husband 'dropped the ball' I think when your son mentioned it, his wife stated what they were doing i.e. camping with her family! He probably feels bad, letting you down, but knows it isn't worth arguing with his wife about?

Not a lot you can do about it except be determined to have a fabulous Christmas doing just what you want and making those arrangements to visit when you can. I feel your disappointment though.