You might also reply to her "This week doesn't work for me, as I'm very busy with some important appointments that can't be moved. I really just wanted to let you know about the ConEd bill, since we had both agreed it was your responsibility. I guess it's probably best to just let our attorneys hash out the legal and financial stuff going forward."
And end it with a STATEMENT like that, NOT anything like "okay?" or anything else that seeks her approval.
