Do you know how when one person gets on your nerves and just bothers you? It is hard not to say something mean to them. Look at what the Bible tells us to do:
Proverbs 15:1 - "A gentle answer turns away wrath, but a harsh word stirs up anger."
When you are angry, it is very hard not to say anything to someone. There's a saying that says, "If you have nothing nice to say, don't say anything at all." I like that saying a lot. But, if you do say anything be kind and gentle about it. It is very hard, I know that from experience. But, if you pray and take a deep breath it can happen. Trust God to give you the right words to say. He will help you.