Windows 2012r2 VHD with wrong size.

I have a physical HDD of 1 tb, I add (somehow) a VHD of 2tb, (sorry newbie here), now I remember somewhere saying that I could do that (add a HDD bigger than the actual size of the physical).
Now my VHD apparently has reached the point to max out the 1 TB, and of course I cheated the VHD to 2 tb, so my problem is now that I had to add another HDD and somehow let Hyper V that it can use this other physical to compensate for the missing space and I have no idea what to do...
So to recap since I know is confusing:
1 physical HDD of 1 TB, I create a Virtual HDD of 2.0 tB (bad idea and I don't even know how I did it)
The VHD has now reached the 1TB and can't save anything else but thinks has 2 TB.
I added a 1 tb physical and need somehow to tell Hyper V, "Hey this space is for the missing 1TB your missing"

I'm so screwed, can somene help me please.