FUCK!!!
I know its a lot of coins, but its easier to help you if you are calm.
-snip-
And why the heck does it need to redownload the blockchain when it still has 46.8GB of blocks?
It does not. I assume that your local database got corrupted. This happens when the client does not shut down properly, e.g. due to a crash. Its rescanning the local data to rebuild its database of TX that are interesting to you because they correspond to your addresses.
This is stupid that the BTC Core crashes so easy then requires a full re-download! Seriously?
Whose dumb idea was that?
If you want to find a reason for the crash consult the debug.log file. I dont know why it "crases so easy" for you. Im running bitcoin core for over a year on several different systems and machines and the only time I had the problem you describe was when we had a power outage.
I am freaking out because blockchain.info has ALWAYS shown my balance just fine, until now.
As Newar said blockchain.info can only show you how much coins have been received on a given address. Your balance is more than that.