What's wrong with you as a teacher ? Celine had told you many times how to pronunce her neme correctly, why did you call her "see-line" all the time? Your job is teaching them English, not making fun of them! Celine Dion is famous singer worldwide, it's your problem to not recognize this name not her!
I am not native speaker but I know what is RESPECT! If you make fun of her name or anyone else, I will have medias and reports to interview you and see what's the fxxk shit in your damn head!