How can I have a complete running version (just like Windows Phone Emulator for Windows Phone 8) of MY OWN windows phone 8 (Lumia 520) on my windows 10 PC?
You can't make an exact copy of your phone image and get it to work on the pc.
Even if you were able to bypass a few security measures, you still wouldn't be able to do it because your phone's operating system was compiled for ARM microprocessor and HyperV (this is what the PC uses for the phone emulator) will require an x86 compiled image.
The best option if you want to use your exact phone on the PC like interface is to use continuum (or the Project My Screen app)
You can use Project my screen app from Microsoft. Which lets you project your phone on screen. Moreover you can control your phone from PC too. Download now. https://www.microsoft.com/en-in/download/details.aspx?id=42536