A spiritual practice or ascesis of thoughts or "guard of the heart" becomes very important for me when I get into any kind of personal conflict in which I feel hurt or angry.
My mind tends to occupy itself with playing out my defensive responses for future, imagined conversations, and going over and over the things that felt frustrating or hurtful.
But all of this is a trick, and if I let myself get more and more committed to living in a world of conversations that might or might not happen, and in any case don't exist right now, I am trading in unreality. And unreality is no-thing, is incapable of carrying meaning, and only leads to further misery.
The ascesis is to notice when the angry, defensive thoughts arise, either before of after they start to coalesce into narratives and "tapes," and decide to let go of them. In their place, I try to simply return to the situation before me, and ask what is called for at this moment, "in the now."
A simple, repeated prayer like the Rosary or the Jesus Prayer can be a big help in this practice: to replace intrusive thoughts that produce anxiety and agitation with holy thoughts that produce patience and peace.