I didn't save the key anywhere. The string of random characters that make up PrivateKey is created using the BrainWallet method, the salt of which is the password I use, consisting of 20 characters (including special characters and numbers), so there is no chance to guess. This was done manually and offline using a tool of my own authorship. I know the mechanisms of private keys very well
So you didn't actually create your private key with Electrum? I'm just thinking out loud here, but it's kind of pointless to generate your private key offline only to later import it into a hot wallet.
Anyway, are you suggesting that Electrum itself is compromised? If so, you might want to share more details so other people can verify where things could have possibly gone wrong. I personally don't believe Electrum has a problem, but that's only because there's no verifiable evidence presented thus far.
I rarely use electrum wallet as their are plenty of breaches to their security and with your current situation it is almost 0% that you can still recover your funds even if you are desperate to take it back.
I can only remember two "breaches", the first of which is inconsequential if the user set a wallet password (with no verified Bitcoin loss), and the other only really affecting alerts which were used for phishing. I'm not going to say those aren't bad, but people who know what they're doing were never really at risk.
Next time it will be best if you use a much more secured wallet like blockchain or your local exchange if you have some so you can easily reach the customer service in case there is a problem in your wallet like this one.
I'd still recommend Electrum over those alternatives to be honest. I also hate to break it to you, but customer service won't help you with anything unless (and maybe not even) they're the one who messed up. So if you got phished or caught a virus which led to your funds being stolen (which could very easily be OP's problem), you're going to end up just as helpless. That means these options are even worse because you have to worry about
two parties messing up (you and them) as opposed to worrying only about yourself.