How can I start fixing my anger issues?

First of all, you need to ask yourself "why am I so angry?"  Once you answer that question  you choose to act according to what's best for everyone in response. If you're truly angry at him, then separate yourself from him for a time and think through the situation.  Finding ways to respond rather than react will help resolve the issue with peace rather than turmoil.  Once you have thought it through, you can then decide how to speak to him about it. 

Anger is an emotion that stems from somewhere else. Identifying what that is will help in understanding why you are getting angry. It could be that you are being triggered from something in the past from a childhood memory, or it could be from a negative act against you or angry words or yelling you have experienced from the past.  Learning to become aware of your circumstances and identifying the source of your anger will help to begin to resolve it.  

Learning some techniques will also be helpful like deep breathing. Taking a time out to separate yourself and think it through, taking a 5 minute walk to calm down and reassess the situation.

Once you feel calm enough to talk about it, you then talk to your boyfriend about your feelings.  Learning to express yourself in a calm manner without name calling, belittling or yelling is imperative.   Knowing the source of your anger helps you to determine these things. Once you are calm and talking to him, it's important to speak with "I statements" to express how you feel.  "I feel (       ) when you (       ).

This conveys the message in clarity and your boyfriend will understand why you're upset and have the chance to respond to your statements. 

Having good communication is also imperative in conflict resolution.  Understanding and knowing yourself well enough to realize why you act and react to each other so that you can resolve the conflict and learn how to speak to each other in the future.  Once you have learned these techniques and put them into practice, you will most certainly find a peaceful way to resolve the conflict.