What wallet software you have used before the hack happens?
You might used a phishing website for MEW or your device's totally infected with malware. Please double check the url you're using and if possible always use an AV.
Hope this will serve as a lesson to you. Btw sorry for the loss.
Yes, this is true, this could have happened because at this time the phishing site was made very similar to the original so that it could outwit the less careful users. Keep careful for everyone, when the price of bitcoin rises, the crime rate will increase too.