So ya got a nasty gram? Par for the course. Sad, sweet, sappy, angry, indignant, rejected, annoyed.. just cycles she runs through. Tomorrow it will be something else. Explaining your point of view never accomplishes anything. Validate and "Gotta go." She is still checking for an emotional connection from you with lil pokes and jabs. When you blow up, are 'there for her', make her a number one priority she knows you're still 'attached'. Any attention brings its own rewards.
This. So much this.
Also, I can only imagine in a limited way what it would be like to say "no" to the kids who want to see Mommy. All I can offer is, despite the preternatural empathy, they are still children, they cannot understand all the ramifications of this dynamic. You are the adult (apparently the only adult in the whole family right now) and it's *OK* for you to make appropriate adult decisions even if they are received with disapprobation. It's no different than "No, we cannot adopt seven pupppies at once." Sweetie, your kids will not hate you; I have no doubt they can feel your love.
"Show me a completely smooth operation and I'll show you someone who's covering mistakes. Real boats rock." -- Frank Herbert