[Skryptec]

The only way I know to see if they're posted online is to reverse search the images. To see who did it, try and look in task manager and look at processes. I believe that was a way to see where your PC is being connected to.

You can see the process in the task manager, yes but if you try to kill it it may not be able to be killed or it will just crash your computer and give you a BSOD.

To see who is connected to your PC is by using Wireshark or shit like that.

The process to remove the malware may be hard if OP's girlfriend got ratted, since the attacker can just interrupt the process.
But I have this beautiful tool laying here which can prevent it