I'm so sorry for your losses. Do whatever feels right for you just now, don't worry about Christmas. Allow yourselves time to grieve. There will be much to do and organize in these first few weeks, Christmas festivities can take a back seat, your mind will not be able to comprehend any sort of " celebration".
We lost my lovely Mum back in June this year, and honestly the first few weeks are still a blur. My OH was a godsend, he took over all the legal stuff, as I was in a bit of a daze.
We certainly couldn't have coped with Christmas as well, in fact I'm having a struggle with it now, I miss her so much.
Please take time for yourselves, and hopefully you can comfort each other. Sending you strength and a big hug.
Take care xx