Your in the eye of the storm right now so it's a matter of taking each hour/day at a time.
have you tried any herbal stress relievers- theres a product here in the uk called rescue remedy-Ask the pharmacist to recommend something
You could talk to your family doctor to see if they could recommend something to get you through the worst of it, if you,re not sleeping they may give you something short term that will help-this madness is easier to deal with if you can manage a few hours sleep
The most thing that helped me was walking-the more anxious I was the faster i walked- I covered miles night and day.
The knot in your stomach will come and go -it will get easier as you adapt. It will pass.
If your not ready to talk on Sunday-tell him you need time and space-it's very difficult because you want to see him but not as he is at the moment.
Can you go and visit some family/friends for a few days-be around people who love you
Understand this Hope-It's not you- it's all about him and until it runs it's course you need to take care of yourself
Set yourself goals for each day-very basic for now but make a list ie. get out of bed get dressed walk the dogs etc... you know what I mean - keep it simple and basic and tick each thing of as you do it.
Over here in the uk we have a 24hour helpline called the samaritians-do a google search for something similar in the states-you might not need them but it's good to have a number handy when you feel you're in crisis-they will call you back if you give them your number.
I admire you for going to work-good on you-you are obviously a strong woman which tells me you'll come through this and know this - you'll be a better person for it-it doesn't feel like it now but it will honey