We used to get in really heated arguments and hurtful things would get said. A few things helped us. One, not to focus on winning the argument. If we won the fight but hurt the feelings of the other person, winning didn't matter. We also got good at de-escalating the other person. Knowing what the cues were and refusing to engage. The hardest was to change our mindset, to look at what the underlying fear/hurt was, not the specifics of the situation. Then to talk through that fear/hurt, instead of arguing about the little details.