The onion link you posted is the Tor version of blockchain.info, I believe. You can either download Tor and log in like normal, or log in using blockchain.info normally. I recommended you back up your wallet next time, since you never know when blockchain.info will go down.  Don't worry, your Bitcoin should be fine. If you have a lot of Bitcoin though, it is better to use a desktop wallet like Electrum if you Don't want to worry about syncing.