Being Christian does not mean, that Christians just lie down and let people walk all over them. It doesn't mean we can't get angry either. Especially when we are constantly defending our beliefs.
We are human. We have human emotions just like you. The difference that makes us Christian is that we believe Jesus as Lord and Saviour and try our very best to follow God's Word (The Bible) When we mess up, we go to God acknowledge our mistake (sin) and ask forgiveness, then we are forgiven just as His Word says.