Conflict becomes productive when the objective changes from victory to understanding the problem.

As long as the aim is winning, every piece of information gets used as a weapon and nothing gets examined. Shift the aim to working out what is actually going on and the same conversation becomes cooperative, because you are both now looking at the problem instead of at each other.

Say the shift out loud. Something like let us work out what is happening here rather than who is right. It is a small move and it changes the physics of the exchange almost immediately.