and I lost the ETH, has anyone ever experienced a similar case to the one I'm currently experiencing?
and how to keep this from happening again? this is really annoying (hacker shit)
The most common attempt of hacking MEW is by phishing. Someone out of nowhere will mail you about your account was compromised or something similar and will give you a link of myetherwallet. If you click that link, it will redirect you to a website similar to MEW. If you logged in using your private key then say goodbye to your ETH and ERC-20 tokens.
Some uses airdrop as a tool. They will intentionally ask for your private key and public key. They will indicate that your private key will be safe and will just be used in verifying if you truly own the public key you provided.
To avoid this from happening again I have some tips for you:
1. NEVER give your private key to anyone. Even though they claim to be someone reputable or known developer of the ICO (or anything) you participated in.
2. NEVER click MEW links in your e-mails. Go to the real website, bookmark it and always use your bookmark.
3. Use Metamask for higher securities.
4. If you'll view your balance, use etherscan or ethplorer instead. Refrain yourself from using MEW just to check balance.
5. ALWAYS check the address bar while accessing your MEW. Check the spelling of the url and check if "MYETHERWALLET LLC [US]" is present. This will ensure you that you're on the right site.
Good information. Adding to this, I would suggest you to keep your private key confidentially. Always keep your private key in a paper wallet or take a printout of it and have it in your safe locker or something where you feel it is safe. Never open any links pertaining to gifting BTC or any kind of attractive offers provided in your email which asks for your private key.