Why do we feel the need to talk when we have worries? 
When our head is overflowing and our heart is heavy, we want to talk about our thoughts and sort them out. In conversations they reach our brain in a different way than if we only think them because we hear them.
The heard and spoken word creates resonance in our self-perception. But the other person also hears things between the lines. These are then reflected and help to find ways out of the misery.