The first thing to bear in mind here is that to feel pain is to be human. There's no way to disentangle the two. All you can do is learn to acknowledge that pain, and assign it a level of importance, then practice that assignation until, suddenly, at some point in the future you'll realise that you've chilled right out.
All this is far easier said than done though.
In the short term, try to practice some level of mindfulness. When you catch yourself being angry, stop and ask yourself where the anger has come from. Is it because you no longer have control over a situation, or because someone has wronged you in some way? Could your anger be useful in resolving the issue, or is it clouding your judgement?
Once you begin interrogating your feelings, you'll find them far easier to understand and control.