Bernie,
My deepest sympathies to you and your family at this most difficult time.
My Uncle passed away 2 weeks before Christmas, 2 years ago and while he wasnt as close as my Father, he was still a very important person in my life and i felt wretched.
I would suggest the same as Spangle, Sean and Amber and keep your card simple, easy to read and full of love.
Can i also add, your Father would probably not want you to spend a sad Christmas - enjoy what you can and when you can and remember that eventhough your Father may not be with you - he will certainly be with you in spirit and will want you to be as happy as you can.
Take care and look after yourself and your family
Flower xx