Sorry but your funds was already stolen and you can't retrieve it anymore. Can you remember the software and apps that you have downloaded to your PC?
Let's say that you have been aware of protecting your security all of the time but you probably missed some random apps that you have downloaded and didn't noticed it as you use them.
it becomes very possible if he has used an app that contains a backdoor etc.
maybe this is my suggestion to use premium antivirus which has banking, payment and cryptocurrency protect features as I use it on my device
and to keep it even safer I recommend closing your webcam for secure your password