[exactly the reason why I do not store any funds on Windows (and Mac) and will never ever do that.]
To be very true, i am feeling anxious as most people use Electrum on the computer and trust it that our funds are safe. What else can we use if we do not have a hardware wallet?
Use a Linux system, but you will have to install the applications yourself from the package manager, and only use portable apps if you verified the release or trust the vendor.
The chances of stock malware breaking into an X Windows desktop on Linux is nil, because they're all written for Windows. You would have to be specifically targeted like Dashjr was in order to be at risk.