When in a dispute, you need to carefully consider both what you and your opponent are arguing. Don't take statements at face value. Try to see where they came from. At every step, ask what was the motivation for that statement? Was it well motivated, or is it being forced? Is there a gap in the logic somewhere?
Emotionally charged arguments are likely to be riddled with logical fallacies. Some of the common fallacies are at
http://www.nizkor.org/features/fallacies/. You need to take a step back and pick apart what both of you are saying. Taking time to think about the arguments will let you pinpoint flaws in your opponent's argument, or in your own.
Also, always try to be objective if you can, and never be in denial if you know you've lost. Acknowledging and learning from your mistakes and moving on is an important part of self-improvement.