Hi Petal! I agree with LaMa. Sometimes you just can't wait to formulate a patient, well thought out reply to someone being a jerk. And sometimes people need to know they are being a jerk! The other day we were all going to a class at the Apple store and my mom started backseat driving in dangerous places where I needed to pay attention and it was raining hard, so I just turned to her and told her I wasn't in the mood to put up with that nonsense today. If she kept doing that I was going to pull over and have J drive instead, and furthermore, it was raining out and I needed to concentrate on driving. She was quiet for a long time and didn't back seat drive. I didn't even think, it just came out of my mouth. It wasn't diplomatic in the slightest, and luckily my mom wasn't in a retaliatory mood and it worked to do that. I could have felt badly, but decided that if someone is going to be an annoying distraction when I have told them not to for years, they are going to get a piece of my mind!
I also don't think it diminished you standing up for yourself by apologizing. In work places it's good to error on the side of being gracious. And those types of situations are really tricky. I think you did well, and should not beat yourself up at all!!! And I hope you don't hide from the person in the future. People get testy sometimes, it's just part of being human!