I sent Davison Design my idea.....?

Ok so in 2008 i sent Davison Design my idea for this product, that i dont really want to say wat it is because i dont want it to get stolen again, and a few months ago I have seen this product, that I feel was my idea!, on various infomercials. But wat happened was I sent them the idea and they contacted me back by phone and sent a packet with papers about the product and fees involved to pursue it being manufactured and whatnot (so i do have stuff in writing) and at the time i really didnt have the funds to send them and honestly i feel the same thing would have happened if i had sent them money, so i didnt contact them back and tried to think of another way to produce it and other ideas and companies. So it wasnt until around Christmas last year that i saw this very idea of mine on an infomercial and I was so surprised, shocked, and after that i felt like i had been robbed and used. I have told a few of my friends and family and I dont think they really believe that i know wat im talking about or think that I am lying. But this really happened and I was 18 then im 21 now and i just need to know if anyone can tell me if there is something I should or can do to get what i may deserve from this or is this just something that happens all the time and I should just let it go???? Please, thank you.