Why am I so quick to get angry?

Stop giving the Aries what he wants. The BEST and most effective way to win with an Aries is to not allow the situation to escalate. You stay calm and reserved and the Aries will get louder, but it will be brief. They WANT you to fight with them and feed the fire. All you need to do is tell them you're not going to participate in their drama, and when they're ready to have a rational and calm discussion they can come and find you. Do not feed the fire so to speak. It works. =)