SPEND TIME with the kids..don't BUY them this year..do what you can..don't overextend yourself.
Take them places, hold them, read a Christmas book to them.. start a tradition.
The "I Spy Christmas Book" is a GREAT one to do together and find things within the gorgeous photos. Provide peace and quiet time. For the younger ones.
The older one's? Write a letter to them not a text or email. Tell them how proud you are of them and how much you love them. LOTS OF HUGS!!!