Is this considered double spend?
This wasn't a double spend, I'm sorry to say, but it looks like your bitcoin was stolen. 

The reason the transaction out says '1 BTC' is that your bitcoin was combined with bitcoin from a bunch of other addresses, and sent all together to that new address. 

You'll have to carefully think about how this might have happened. If your wallet was backed up by email, it may simply be that your email account was compromised. 

Again, sorry for your losses :(