Promotion versus Integrity

Recently I was promoted into a Lead position at work. I was glad for the promotion, especially considering I haven’t been here quite a year and my last job I was there almost 5 and I NEVER got recognized or promoted or a raise for that matter. And now that I’ve gotten this promotion I don’t want to look a gift horse in the mouth – but I am annoyed by a little something called nepotism.
The other person who was also named a Lead is now getting ready to abandon us and go to a different department. A department that I’ve been trying to get into since before I got hired for the job I am doing now, a department that I am more qualified to be in than the STUPID supervisor.
So why, you maybe asking yourself is this other person getting the transfer while I sit here stuck in the dungeon? One word: NEPOTISM. Because this other person flirts, are skinny and a bimbo they’re getting the transfer, since I refuse to use anything other than my skills and brain to get what I want, I sit stuck.
Now not only am I faced with this annoyance but ALSO the moral dilemma on whether to tell my supervisor this is happening behind her back or not. I don't want to be a tattle tale yet I also don't think its work ethical for them to go behind my bosses back to plan this. Why do people have to be shady and underhanded? Why isn’t job integrity and morality important anymore? Come on people at the end of the day do you want to have integrity or a promotion.