Arbitragecoins.com is the scam site.
Why the hell did I send coin to that site? It was because of all the hype on the Arbitrage Bot: https://www.arbitraging.co
FOMO got the best of me and I was dumb.
I know that FOMO is really a strong instinct, as a human we sometimes do become impractical when we feel a strong force that compels us to act before we think. the Fear Of Missing Out is something that we should consider when we see a very lucrative offer online, as people here have mentioned, the saying "if its too good to be true then it probably is." is really old but is still very valid in todays situation of all these scams on the internet.
No you are not dumb if you only followed your emotions its more of that you were not prepared and that you were GREEDY. Yes that is the term that you should understand that pushed you into being scammed. Greed is good only in games. In real life it can make you go bankrupt.
Another point that I could advise on in the future if anyone asks for your private key, is to NEVER, EVER give out. Its called private for a reason. Treat it like its your password, if you give it out, people can access your accounts, in this situation its your wallet with your money in it. Ask yourself this do you give out your password online? The answer should be no and that is how you should treat your private key.