Very angry with ex nanny

She has worked with us for 4 years. Last year my husband and I separated and so she worked in between mine and ex's home.
I told her a few weeks ago that I was moving house. She doesn't drive so I asked about her thoughts on it all and what we should do. She mentioned extra time and expenses and then said she wished I had told her sooner so she could plan for the new school term. She then said she could only now work for my ex.
I told my child that she had chosen not to work for me anymore. Last night I got a text from her saying she had corrected my son and told him the reason why was because I wasn't paying extra time and costs. I told her I was not happy with this as at no point had I said I wouldn't pay. She said 'You never mentioned that you would pay them once. If you wanted me to work for you still, that's the first thing you would have done. I feel hurt and disappointed at how this has been handled.'

I am very angry. What should I say in return?