Probably best you stood down if the argument was only going to lead to trouble. I've stuck to my guns about (unrelated) things and ended up spending nights on the couch for quite some time as a result. Perhaps if/when there is a time you believe you can converse without getting into an argument about it, you might state your case, and explain why (which doesn't mean you have to out yourself, but rather explain exactly how prejudice is harmful).
Ironically, this is cd myth #7... which isn't quite ready yet. It would be great if your wife ever found her way to the
crossdressing myths some time. Not that she'd ever going looking for them on her own...