The Bible tells us that anger is a very dangerous emotion and warns us to be constantly on guard against it. The Bible says, "An angry man stirs up dissension, and a hot-tempered one commits many sins" (Proverbs 29:22).
Does this mean anger is never justified, or that it is always wrong? No, not necessarily. The Bible says God is angry when people sin and deliberately turn their backs on Him: "For forty years I was angry with that generation; I said, 'They are a people whose hearts go astray'" (Psalm 95:10). Jesus also became angry when He saw men making money from God's temple, and He forcibly drove them away (see Matthew 21:12).
In other words, we must never take evil lightly, and anger against injustice and wrongdoing has its place. But when we are angry at someone, we have to stop and ask ourselves why. Is it because we know God is offended or is it only because they have hurt us, and we want revenge? If the latter is the case, then our anger is wrong.
Instead, let the Bible be your guide: "'In your anger do not sin': Do not let the sun go down while you are still angry" (Ephesians 4:26). Yes, what your brother did was wrong. But ask God to help you to forgive him for if you don't, your anger will become like a poison to your soul.