First off-
Make your appatizers easy- some nice cheese, crackers, a veggie plate and dip. Put your husband in charge of circulating the aps and making sure everyone has a drink or glass of punch or whatever. That leaves you free in the kitchen!
I would ask other people to bring a few salads and rolls. Those things are easy and with such a big group I'm sure people will want to give you a hand.
Make scalloped potatoes with cheese to go with the ham. They're easy and can be made in a casserole ahead of time (like today!) and then heated up for the dinner.
Another nice, elegant and easy side is green beans with walnuts. This is actually even less work than traditional green bean casserole and if you have some more health conscious guests, it would be a lot less sodium, etc. for then as well.
Steam the green beans on the stove or in the microwave- be careful not to over cook them. They should be bright green and still have a little 'crunch' when you bite them. Then heat up a skillet, and put some crushed walnuts or hazelnuts in with a little butter. Cook the nuts until they are darkened and the butter is browned. Then add the beans and a little more butter if you need it to give the beans a light coating. Stir fry them up - and you have a lovely green veggie to go with your main course.
For dessert, I would just have a bunch of cookies or little things- everyone will be full from the main meal and will just want to 'pick' at dessert anyway. You could even ask everyone to bring a dozen, and then all share what you made. Have a wonderful holiday- I'm sure it will be a huge success!