I'm not going to give you legal advice here, because obviously this is a site for startups and not jurisprudence. But I would ask a few questions here.
First, just how novel is your idea? How sure are you that you and he are the first people to think of this? If you weren't the first (and no disrespect, you probably weren't), and someone has something resembling prior art out there, then it doesn't matter.
Second, do you believe he is really applying for a patent? He might just be full of it, and think that phrase on his page impresses people. It's not that easy to do, and it ain't free, so what are the chances he really is? I would venture to guess that any twit who would drop a phrase like, "friends don't litigate friends", has delusions about becoming Mark Zuckerberg or something and having Google buy his awesome product.
Thirdly, say you really believe you do have a novel idea, and really believe he is patenting it. Go straight to a patent lawyer, and get advice on this. Don't ask anyone else's opinion, go straight to an expert. He/she will tell you how to properly handle this, and if you could successfully litigate. Patent law is so crazy, amateur advice might screw up any chance you have of challenging him.
Most likely, the whole patent thing is moot; neither of you could patent it, someone already has the necessary IP and you couldn't afford to challenge infringers anyway. So stop worrying about it, and if you're a product guy and not just an idea guy, build the product and beat him. So what if he beats you to market; figure out his product's weakness and beat him. I don't mean to be trite, but end users buy products, not ideas for products.