So, so sorry to hear your awful news. As others have said, a parent’s worst fear. There’s been a lot of good advice already, and not much I can add, but the hospital may well have someone to speak to for advice right now, and be able to put you in touch with some local support for you and the kids too.
On a separate note, it never fails to astound me what a good place this is to come when you really need some support. For all the banter and bickering, there are some truly thoughtful and caring people on this site.
Thinking of you all, and as others have said, try not to keep it in.