My suggestion is: one or more flashbacks. Flashbacks can really make a scene more emotional if you can write a relevant and sympathetic flashback. This can be used for either the villian, the hero, or both. This can be as simple as a few images of memory, or a full on flashback scene. The purpose of the flashbacks would be to solidify the justifications of each side. Or another option would be to give a flashback to the hero that at first seems to justify the hero's actions, but upon further inspection and upon deeper conversation with the villian it is revealed that the more the hero considers their words the more they can see how they misinterpreted the events of the flashback.
Other tools to use-a lot of intense closeups. The goal is to build tension before the outburst of emotion, you want to show some hesitation in the hero as they muddle through their thoughts on the issue. So do this by first showing close ups of some body language. Kinda depends on what your characters are doing, but showing things that are common forms of insecurity/discomfort (rubbing the knuckles of one hand with another, fidgeting with an earring, ring, some other object, playing with your hair/facial hair, scratching the side of your arm, looking at the ground and kicking a small stone, etc etc etc- I'm not saying all of these are what you should use just these are examples, and you decide based on the quirks of your character) Show little partial panels of closeups of some of these actions to display the discomfort of the character while the conversation is happening. Then as the situation is building up or when someone is making a strong point you have intense closeups on their face showing strong emotions. It doesn't have to always be just the face, it could be parts of the face, just the eyes, or the mouth, etc. Or it could be the whole face, really depends. Usually a mixture helps.