My shitty third floor slumlord apartment has old knob and tube wiring in it. So it obviously has no grounds. I don't want to fuck up my computers, so I'm trying to ground an outlet in one room.

There is a cast iron fire escape just outside the window that is stuck directly into the earth. I drilled and attached a solid 12ga insulated earth wire to it, and ran it in a small hole I drilled in the window frame. I used this wire to ground a new GFCI outlet I installed. It all checks out electrically, and my computers work fine.. But is this safe long term? I've asked, the landlord will not rewire..