Really CIPA, based on history, I'm not sure there's much you can do to keep this from escalating. So what you need to do is make this an opportunity for you.
When she blows up....and she very will might, listen calmly and let her go off. You don't have to answer any questions. And tell her that should she ask them. Here's what I see might be said/asked.
"How can you say no? This is for your child." CIPA "I always have my sons covered. What you are asking for is the part YOU were supposed to pay for. So really, let me ask you, how can you not have the money for this? This is for your son?"
"I can't believe you're being so stingy, so mean." CIPA You say nothing. As a matter of fact you say nothing to any statement she says. This is something I learned as a reporter. During interviews people would make statements and expect a response from me. I would say nothing. Rattled them. It was even worse when they would ask me a question. Let her say/ask whatever she wants but you don't owe her anything.
