Never explain - your friends do not need it and your enemies will not believe you anyway.

Most of the energy in a long defence goes toward an audience that was never going to be moved by it. People who trust you already grant you the benefit of the doubt, and people who have decided against you will treat whatever you say as further evidence. What remains is your own discomfort, which is usually the real engine of the explaining. That discomfort is worth feeling rather than spreading around.

The next time you start to justify yourself, ask who you are talking to and whether words will change them. Give the facts once, briefly, and let the rest stand.