Told my WAH no contact 3 days ago, and now I do want to be with him on Christmas. Thought I could do it, but am crying almost constantly. Most of the advise is to continue NC, and maybe if it wasn't the holiday season, I could. But I feel the mental anguish is making me physically ill

You're doing it to yourself. If you were Muslim, for example, this Sunday coming would just be another Sunday. So, please, this is where push comes to shove in keeping the course... it's just 24 hours (not even, since you're asleep during some of that time), it will pass easier if you don't dwell on it, dwelling on things is what causes these feelings to come forth.

Plan something else if you can, go to the movie, something. You'll feel so much stronger the next day. If you relent, you may not feel so strong. Let the No Contact have time to work. Holidays interfere with that because they distract, so you have to give it a bit longer around this time.

Any advise is greatly appreciated--no matter what you tell me!

Stay with one thread at a time.