That unfortunately sounds like a rootkit, which is the most-est mal of all malware types. By disabling your computer's protection against malware you've allowed it to replace any file it desired on your PC. This includes all your system files, program files and data files. It's virtually impossible to be sure you've cleaned it out, no matter how thorough you clean things with any antimalware or antivirus because you've given the malware freedom to replace any hash/parity protection your files had.
The best solution is to remove all partitions on your drives. All drives that has been in your PC since you installed it. Re-flashing the computers BIOS is also a worthwhile precaution as a modern BIOS really is a small independent PC running beneath your PC, with its own operating system and storage. Instructions on how to flash your BIOS can be found on your PC's or motherboard manufacturer's support website.
Don't back up any program or application files. If you have important documents or other data you need to keep, back it up to a separate destination like a DVD or clean flash drive. Try to avoid using it for a long while and only open it with an up to date antivirus (this to increase the chance that the antivirus will have the malware in its database of known dittos). Now, it is very likely that the malware will be powerless on a clean and reinstalled PC as long as you ensure your protection is up to date and fully running when you access any backed up files, otherwise it would most likely not have tricked you into disabling it all. So, this would mean that whatever you backup should be restore-able. Should be. Not necessarily guaranteed, but almost guaranteed.

In the future, never download games or apps from torrent sites. Not even "trusted" torrent sites. If it's pirated you will never know what you install. Steam game keys can often be purchased really cheap on discount sites like Kinguin. That's the best protection against malware. They'd have to hack Valve or Origin to get their malware onto your PC through the big game ecosystems.
