Video: Six Day War Massacre: USS Liberty Veterans Reveal Truth About Israeli Attack (Part 1)
Cognitive dissonance is no joke.
If you show someone that 100% of what they assume to be true is a lie, they might have to spend literal years acclimating to that reality.
The Matrix first movie makes an analogy to this situation, the whole Morpheus speech on how some people become so dependent on the system of lies that they fight to protect it. It really happens IRL.
That's the first reaction, if one can calm down then assimilation of the information given is possible.