Someone has wronged you, lied to you, cheated you, or worse. You're not only hurt, but angry. Maybe even feeling betrayed. When something like this happens, it's easy to do the wrong thing.
It's easy to complain about the other person to your friends and coworkers. Perhaps a sarcastic or biting remark on social media comes out. The longer you go, the more foolish the actions by both parties. There's really only one, best and only way to deal with conflict.
Talk directly to the offending party and work it out. Period.
Anything else is beating around the bush and putting a relationship in jeopardy. Maybe you can't resolve the disagreement and unfortunately never gain back that trust. Even so, voice your grievances to that person and that person only, then lay it to rest.