NEVER EVER give or post private key (private address, sometime or usually a password, encryption for the wallet...) to anyone. Balance in wallet is just imaginary, coins are really on a blockchain and the private key is the only access to get to them.
Remember, you are your own bank in that case! If you have coins on Bittrex or Poloniex or any other online exchange, you basically dont own private keys and in worst case scenario (hack, shutdown, theft...) you will loose everything. ---> Best thing to do is to get Ledger Nano S (asap, right now it still unavailable..) cause it can store a lot of coins and also all tokens (Humaniq, Golem, Iconomi, Gnosis...) for Ethereum network and is the safest storage possible. Especially for that kind of money... And you dont need to download blockchain which is over 100GB for BTC and LTC combined. And there is at least 15GBGB or many more for Ethereum at the moment... No brainer to get the Nano S or similar capable hardware wallet.