How do you defend yourself when in a personal argument or when criticized? How do you react internally?
I evaluate the criticism. Invalid criticisms are discarded and/or ignored. Criticisms that appear to be due to misunderstanding are responded to and corrected. Criticisms that appear to be valid are taken under consideration and I adjust behaviour accordingly. Even if the criticizing individual is ill-intentioned, I can still use it to improve myself.
Do you prefer to avoid confrontation, create confrontation, or is it more of a case by case thing for you?
Diplomacy and tact are preferred in any situation, though not always feasible. Direct confrontation is preferable regardless. Approach me and I will respond if the request seems reasonable. I'm not likely to enter in to a confrontation without seeing a benefit. It's a matter of energy expenditure versus payoff.
Do you hold grudges or find it easy to let things go?
It depends on the situation. In general, I do not hold long-term grudges. It's usually not worth the effort it takes to continue to fuel such things. There are a few occasions in which I felt deeply, personally insulted and held a grudge on matter of principle. Those are, however, extremely rare. Most of those have been paid off, but some take years. I have two left.
If you don't let something go easily, is it because you think the other person is wrong, or is it more because you like to be thorough and get closure, finding that more constructive than evading or sweeping the issue under the rug?
It's a little bit of all of those plus the additional proof to myself that something is accomplishable and principle of the matter. For example, a career counselor telling me that "sometimes people with your types of disability [he meant PD] can't always do the things they think they can do" leading to 12 years of school and advanced degrees.
Basically, how do you deal with potential conflict or antagonism?
Initially by evaluating the expenditure involved versus the payoff received and deciding if it's worth addressing. Then responding accordingly.