It's going to hurt like hell. Feeling sick, not sleeping, not interested in food, can't stop thinking about it - all totally normal.
You've had a shock and it takes time to get over it. But you will get over it - I promise you. Truly you really will. You just have to get through this epically shitty bit first.
Be very gentle with yourself. You'll want to dwell and wonder why you didn't see red flags before, worry about your future. All normal but try not to dwell too much. You can't change what's happened, and you don't know what's coming in the future - all you can do is focus on now.
Eat. You won't feel like it, but not eating won't help your energy levels. Try soup - gentle on your tummy and isn't too bulky.
Exercise - not some kind of mad gym bunny routine (unless you feel like it!) but try and get out for some fresh air and a walk every day.
Don't isolate yourself. You'll be tempted to shut yourself away - don't. Spend time with family and any friends that have free time. Don't spend Christmas on your own. Your family love you and it won't make their day any better if they know you've taken yourself off because you're worried about being a burden - it will just make them worry more. So spend Christmas with your family.
One day at a time. You feel like your heart is literally breaking right now - it will pass. It doesn't feel like it now, but it will and you just have to take each day as it comes.