The best thing I learned for controlling emotions is "mindful meditation". It helps one get to the here and now. This can help us separate our thoughts from the emotion that is bothering us.
Sit in a comfortable position with your hands on the seat or in your lap. Slowly breathe in through your nose and out your mouth rythmically. Once you feel relaxed enough, focus your mind on your other senses. How does the seat feel below you? The temperature of the room? The smells? Take in all that you can, one thing at a time.
If you find yourself trailing off, start over. For example: The couch feels bumpy yet soft.. I got it at the flea market in town.. I am stressed because I got in a fight there today. You should only pay attention to your senses for this.
With practice, this meditation is very valuable and will become easy to do on the spot.