It's hard not to get defensive under normal circumstances. But to do so when you have opened yourself up for attack is even harder.
Set some base rules up for yourself. Maybe a 24 hour rule. If she attacks, you tell her you will listen but that you will not react until 24 hours have passed to calm down and really listen to what she said.
If that won't work because she wants an immediate response, maybe get in the habit of asking one or two clarifying questions or restate the question a different way to give yourself the time to calm down and respond rationally.
Are you dealing is anger issues in IC?