Are you kidding by using the word "stole"? Doesn't instagram have the right for building a web profile page for each user with the photos it acquired? Ok, your service is nice too, but as i see examples of instagram pages, their service (at least design) is way too better than yours. Don't get me wrong, if i were you, i would be pissed off too. But there is nothing stolen from anywhere. Take a step further, build something adds value to an existing product, like you did before.
Protip: when you write tounge-in-cheek, <parody> tags are required for some readers.