I remember the year we got dd.
I remember having to tell friends of ours - we had already adopted ds; he was only two, and we got dd with only 2 days notice. They had started the process a short while after us, and there we were with two children when they had none at all.
and then, when dd was just short of a year old I discovered I was pregnant. I was dreading telling them really dreading it. They arrived on our doorstep when I was 8 weeks pregnant and puking my guts up, which I had to hide.
But they had come to tell us they had been matched, and they took their daughter home the following week 
. She was almost exactly a year younger than dd.
I look at the two girls now, fifteen years later, and I feel absolute horror at the fact that they might have dd and we might have their dd. Which would be absolutely and utterly wronger than wrong (nice though their dd is, I can't imagine life without mine).
This, added to the fact that a change of social worker meant we got ds1 rather than the child we were meant to get a year earlier (our social worker moved job without completing our paperwork) means that fate gave us all our children. And the thought that they might be somewhere in the world, with another family, other parents, others friends and schools and lives is just unthinkable.
So I have every sympathy for you. I was also resentful, and jealous, and bitter (and quite frankly pretty nasty 
) for a time. But, now, my children are my children, and I can't imagine life without them.
You will survive Christmas - we have all done it.
And when you do have your family, this will be in the slightly embarrassing (and probably wryly amusing) past.
Honestly, it will. Chin up. You are allowed to grieve, to be lonely, to be bitter and jealous and horrible. Here's a good place to do it. And in a few years' time you will be comforting someone else 
(with no Christmas hat on my smile, because that might be rubbing your nose in the festive season which I'm sure doesn't feel too festive atm).