just realised this is you...
I know that in your heart you probably think that this is the best and easiest option, to get back together with him, but the other posters are right, you need to take a step back and think about what happened before. Reread some of your original threads, how you felt when he first left. (I just have skimmed them). Do you want to feel like that again? Can you cope again if you get back together and then split up again?
Your older children have seen everything that you have gone through and will feel very protective of you. They won't want to see you get hurt again.
yes sometimes people can change and things can change, but he needs to spend a very long time earning your trust back and their trust back before things proceed.
Can there be a compromise, in that he comes round later on Christmas day for a few hours, so that he is not there all day?
But really, do have a long long think about what YOU want out of all of this and how it will affect everybody if it goes wrong again. I know a couple who are divorced and have tried twice since then to get back together. Each time they do, and it goes wrong, it just confuses the children more and more.
Best wishes X