Input lag with vsync on, tearing with vsync off. Help??

hey, so I'm currently having to play DBD with my PC connected up to my 50" 4k TV as my cats broke my monitor. ever since I hooked the PC up to the TV the game performance has been awful. it worked perfectly fine on monitor but not on this TV.

Input lag is the main issue. I can't pass any skill checks due to it and even turning my character with the mouse is delayed.

I tried to turn Vsync off to fix this, which it did fix the input lag, but it caused awful tearing all over the screen.

I've tried turning down FPS, graphics, resolution, everything and it's either come down to awful screen tearing or awful input delay. any advice is appreciated!

(I'm on a windows 10 PC with a NVIDIA GTX 970 GPU, which used to run DBD fine) is it a PC issue, game issue or TV issue???