Yeah, I hate it when stuff like that happens. But you know what? The more friends that you share your idea with, the more people can bounce ideas off you, and all together you'll be able to come up with a really well rounded idea. So don't hide your ideas, just keep developing them, and consider the concept that your first idea maybe isn't always the best one, and just to keep working and improving. Because if you don't try and push yourself further, you're not going to get any better right? So just keep at it.