you know your ex wife is using a language your current wife does not understand to do exactly that, to piss off your wife and make her have doubts about you and ex. you should get your wife a dictionary and proove to her you are not lying to her. it wouldn't hurt to mention that your wife now understands German and that she thinks it's fun to know a different language and that you are also having fun e-mailing ex in German. maybe ex will give up and write in english. Have fun , just do it as a comment or conversation dont say it as an insult. 