We actually ended up having a great time at my SIL's. Because it wasn't Christmas Day itself and was so different from my own family Christmases, I was able to do my grinch thing and pretend to myself that it was just another ordinary day and we weren't trying to celebrate the most family-friendly and child-centred day of the year, and that made everything much more bearable. But it was also great that I got to know my SIL a bit better.
We were doing some clearing up in the kitchen, and for the first time since we arrived, she and I were on our own. I knew DH had told her about our IVF attempts, and as soon as everyone else had disappeared, she said, "I'm so sorry about the IVF."
We then had a really good chat - I filled her in on some of the details and what our next plans are (they've changed a little bit - I'll fill you in over the next couple of days). We talked about how hard it is, and I even confessed that although I was sad that our plans had had to change because of the snow, I had also been a bit relieved because I didn't know how I was going to cope with such a child-centred family occasion so soon after our BFN.
And you know what? She understood! And I finally felt close enough to her to be able to ask the question to which my DH hadn't known the answer - did she and my BIL have to wait long after they started trying before their first child came along? I had suspected they might have had problems, partly because they'd been married for 13 years when their first child was born and partly for other reasons.
And sure enough, she said that they were trying for over two years before she got pregnant with the first one. And she understood about people making insensitive remarks, and about how soul-destroying it is to be disappointed month after month, and about how difficult big family occasions can be.
And suddenly I feel as though I have another ally in all of this. I hate this being the connection that I have with her, but I'm glad I've made a real connection. I just hope one day I'll be able to produce a little cousin or two for her children.