If you feel the need to respond back, I would suggest something like this: "h, I'm sorry you feel the way that you do towards me and the situation here, but I need some time to think about what you've posted for a day or so and then let's sit down and talk about this."
You do need some time to calm down and truly think about his comments and when you do have a meet up w/him, stay calm, keep your voice calm and even and always look him in the eyes. If something isn't clear, repeat it back to him and see if you have understood him correctly.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
