I think someone else said this below, but this sounds like grief.

I hope that you can get to a place where you can face it but be gentle with yourself along the way. This stuff is so messy and painful.

You seem like an immensly strong person but actually sometimes it's necessary not to be strong and to allow our inner whatever (child? vulnerable person? I don't know) to take over. Really hard with kids I know. I hope that the lifting of holiday expectations helps to give you some space for you.