I think you got phishing , that's why you need to bookmark MEW, it's better than typing it . MEW will not be responsible for your lost . Always protect your private key don't give it to any mysterious site ,
Bookmarking the legit site is the best way to make sure you are not phished by scam websites but when we have other problems like keyloggers...
I think the use of private keys needs to be used with metamask or a Hardware Wallet to prevent being phished.