This is your friend's perception and they seem judgmental.
You may want to think about what may have caused your behavior. People make mistakes. You may also not want to feel guilt especially if you were not involved with someone else at the time of your trip out of town.
Let your friends know that you're trying to figure out what happened during your trip, and that you're working on yourself in that regard. Just keep it a matter of fact and do not offer them any more information about that issue except perhaps that was a misjudgment on your part.
If these are trusted friends, you should not fear your reputation.
Exercise caution in what you share even with those you consider "best friends". Even a best friend can exercise some objectivity when you share something that was on your mind.