You're right; anger is a sin in God's eyes, and you need to face that truth honestly. Jesus warned, "I tell you that anyone who is angry with his brother will be subject to judgment" (Matthew 5:22).
But have you ever asked yourself why God takes anger so seriously and urges us to cast it out of our lives? One reason is because of what it does to other people. When we lash out at someone, we hurt them and create conflict with them -- and that's wrong. God loves them just as He loves us, and when we hurt someone through our anger, we're hurting someone God loves. The Bible says, "An angry man stirs up dissension, and a hot-tempered one commits many sins" (Proverbs 29:22).
God also hates anger because of what it does to us. Anger cuts us off from other people; no one likes someone who may explode over the smallest thing. But anger also twists us and turns us into bitter, unloving people. No wonder the Bible bluntly warns us that "anger resides in the lap of fools" (Ecclesiastes 7:9).
Begin by turning to God and asking Him to forgive you for all your sins -- including your anger. Then commit your life to Christ and ask Him to take away your anger and fill you with His love. Once you realize how much God loves both you and other people, your anger will begin to fade.