You don’t. They won’t provide you a chance to find a hole in their statement, and if you do, they’ll attempt overpowering through intense heat/anger to cause a retreat. Especially so if they’re emotionally unhealthy. You can back off and find another time to speak to them when they’ve cooled off.

However, I find it more effective to deal with the situation there and then. You can either match their intensity and fight fire-with-fire, call them out for not being in control of their emotions or if you dare to against a parent, jab them with « you’re setting a great example for your children right now. »