I am feeling very sad for you. I always say that it is very bad idea to store your btc in PC because PC has very weak security against malware. I believe that your PC also targeted by malicious activity where Hackers get access to your phrase. This could be only reason of your loss after reading your full story.

Why I am saying PC is not safe? First of all we Install Window, or Linux from shop(most of time we purchase PC with built in Window). Shop member generally using crack windows which have built in drivers and other needful software. These windows download from Unofficial sites and the chances of malware is so high. Second whenever we install any software especially when crack or any app from unofficial app , These apps are also full if malware. sometimes app automatically installed with popup when we browsing when we have strong security against malware.

Sad to say that No one can return your BTC even Satoshi but I am sharing strategy for future which will prevent you from further loss

▪️ Download official window from office site and make bootable usb by own.
▪️Don't use old this hacked wallet more and also If you used any other btc or altcoins wallet kindly send funds to new wallet (Create with mobile)
▪️Don't install unofficial software. It will be better that you use two PC. One should be fully spare just for crypto transaction