Not sure what to do about this situation.?

Im married to a wonderful woman and I love her very much but I have a secret that I cant get rid of. I have wanted to be a girl ever since I can remember and I have been pushing this desire away as much as possible but lately the more I try to push it away, the harder it is. Im scared to tell my wife because I dont want to hurt her or lose her because I love her very much but at the same time, it gets harder to keep this secret from her. Im almost certain that if I told her she would leave me and that is the last thing in the world I would want to do. I know im not supposed to feel this way but I cant help it. We are both 24 years old and she is VERY attractive and it would be VERY easy for her to find someone who isnt cursed with this mess but it would kill me if she left. What should I do? I dont even know who to talk to about this without it getting back to her somehow. HELP!!!!!