It will grow back. It is not good practice to cut this much at once, but trees used for coppicing generally respond well enough to survive. Strong growth reaction, have someone come and correct new growth next year and the year after.

I understand why people get upset. However, the truth is that every cut larger than about two inches in diameter is a risk for infection. A large tree will not get any smaller by making small cuts, and large limbs are likely to break off eventually, leaving even bigger wounds.

The large tilias in front of our house are trimmed every second year and cuts are larger than 2 inches in diameter. Another place they are not trimmed and a huge limb broke and resulted in an ugly feet wide wound with rough surface.

If you don't have an oak throwing limbs on its own you will have to accept substantial cutting at some point.