I agree with this on every point. You don't share your fantastic idea because it's original and unique - but if you go to any startup event you'll probably hear your idea, or some variation thereof, discussed. Most certainly, a VC has heard your idea a time or two (or more). ORIGINAL ideas are really not that original. If people are speaking of your idea in such an exclusive forum, imagine how many people have had your idea that never talk about it? Do a patent search sometime with your keywords and it will depress you.

But while being depressed, recognize that it really does boil down to execution - a phrase I absolutely hate, but have had to surrender to. It's true.

Competition is good! If this got you down, consider it a favor - they saved you time and money. You don't have what it takes (harsh, perhaps - but the truth in a literal sense. I suspect you'll get past this). Having a competitor is the most favorable of obstacles you'll encounter.

Don't give up. Keep at it and do it better than anyone else can do it. If you love it, you'll do it.

Best wishes.