I feel for you and your children.
My 1st DH died by his own hand on Xmas Day 1994. I was pregnant with my son at the time and determined that Christmas would not be spoiled for him by it being the anniversary of his father's death. We would go to visit DH's grave about a week before Christmas to put some flowers on it then we would go somewhere that he wanted to go to. Actually, we still do this, though these days it costs me more than a Happy Meal(!)
Over the years we have done several things - we've stayed with my parents, my PIL & had Christmas in our own house - either with one or other set of DS's grandparents, but some years just the two of us. That was until I re-married when DS was about 13 years old. I didn't even think about dating until DS started secondary school and ended up marrying someone who I'd known for years and had been a friend of the family and very familiar to DS as a friend who used to take him to rugby, football etc.
Not Christmas - related, but I made a 'daddy box' for DS with photographs and little mementos (the heather that DS wore in his button-hole when we got married & I'd dried, DH's school reports-that kind of thing) . Every year we would write him a Christmas card and put it in the box. But I needed to make his daddy 'real' to DS as he never knew him. DS treasures this box-though the original shoe box has long-since fallen apart and several years ago I bought him something bigger & stronger. However possibly you could do similar with your children & they can decide what to put in their boxes? It can help to prompt questions, discussions & allows children to express their feelings & their grief.
So, I would say do Christmas your own way - ask the children what they would like. They may want a full turkey dinner with all the trimmings or they may prefer to have fish fingers & chips. Encourage them to make Christmas there's in the way that they would want to celebrate. Obviously you will need to have suggestions of your own. I would also suggest that you are flexible as it's going to be tough on you all this year.
Good luck and I will be thinking about you this Christmas.
It must be very raw at the moment, you will never stop missing him, but the pain becomes easier to bear. 😘