You don't want a patent, you want an NDA.
See a lawyer.
+1
if you believe your Idea is really good you need a patent lawyer to make sure you don't screw up a patent. it will be quite expensive though if it is even possible to patent/copyright your app.
there is nothing wrong with asking this question here despite the usual 50% unfriendly responses that you get here for every type of question. however legal stuff needs to be done by a lawyer.