It's not that your defensive reaction isn't understandable, because it is. I have a whole thread about how I still feel defensive when folks point out where I've been unintentionally harmful. The trick is not letting that feeling get in the way of behaving decently, regardless.
EbOn reflection, a lot of my automatic defensive response was about feeling ashamed and embarrassed to be caught using harmful language, and more, about not having realized the language was harmful to begin with. Which led to me wanting to deny that the language actually was harmful.