"Food was substituting for every kind of engagement."
This is a huge realization. Congratulations! I really mean it. And of course it's a depressing thought, since you know in your heart that you are worthy of so much more. As you will have read in the fasting lit., almost everyone feels really miserable, lonely and depressed in the first few days.
You just tough it out. It does get easier. When it's hard, just tell yourself that any brief comfort eating something might give you will still be there ten days from now, and for this brief time, you are taking a break. (Meanwhile, your attitude toward food will change)