first christmas after a loss of a parent

Hello,this may seem like a very odd question but i am in such a strange place,first loss as a grown up and really struggling.I lost my dad almost 6 weeks ago unexpectly and christmas is stressing me out dad loved christmas my birthday is christmas day 61 this year and apart from buying for my son/daughter inlaw which will be money this year i will buy for my 2 grandchildren age 4 and 2 that's just one trip to smyths toys my 4 year old grandchild thinks its the best store in the world,i have decided to do nothing no cards,gift,xmas food or christmas tree it will just be a normal day for me and hubby in our house.My question is what did you do first christmas after a loss so close to christmas do you think i am silly wanting it to pass me by with no celebration apart from visiting the children,i really don't see in joy in anything at the moment so why should i just pretend i am okay,hubby is happy to go along with whatever i want,but i have had people say your dad wouldn't want you to be so sad,its the only way i can cope at the moment,i think my mum and sister who lives with her may put up a tree which is my sisters choice mum says she will struggle to get through the day and will just go along with whatever.It is just a tree but no dad equals no christmas to me any advice please.Many thanks