Why did you keep all your life savings in BTC? I really don't get it. Unfortunately the only thing that you can do now is analyse your actions step by step to find out which software has been compromised. You either have a trojan on your computer or downloaded fake wallets that had a backdoor allowing the hacker to get your keys.
The money is gone either way, calm down, have some alcohol or try to get some sleep. The sooner you get over it the better for your health.
It is a really unfortunate situation, most probably he tried to extract the fork coins using the private keys keeping the bitcoin in the wallet and that is the biggest mistake he did, we have discussed about extracting the new coins and how to do it safely, the risk of using your private key with the coins in it is the most damaging thing you can do. I am not even sure who is behind BTC Diamond and BTC Private and i have not extracted anything till now, the only coin i moved is BCH and that too first moving my bitcoin to another wallet and that is the safest way.