Yes, you should tell at least your mother. She will eventually find out anyway. Learn as much as you can about crossdressing off www.google.com and then try to explain how you feel to your mother. I have no doubt she will be shocked at first, but she loves you and you can both work from there.
I believe that, although it will be very, very hard, you should try to tell your mother. There are many other answers on crossdressing on this website, which can all be of great help. Your mother will most likely understand and will help you to decide whether you want to continue dressing, and if you do, she will likely understand. Many people in the world crossdress; you are not alone. Your mom will not be enraged, just shocked. Everything will turn out better than it was before, and a huge burden will be lifted off of your shoulders.
By all means , tell your Mother. If she goes up in smoke , ask her to take you to a therapist. The therapist can explain it to her , and also help you understand it better yourself. If you have other tendencies or confusion, the therapist can help you identify just what's going on with you and suggest a way for the family to accept whatever the final decision is, and how to deal with it as a family.