Definitely the damage is serious, and it cannot be repaired only by gluing up the two broken pieces together. Making a new headstock is the only solution of the problem.
I made a new 5 piece Maple blank, which has the same construction as the ordinal once. The only difference is in the color of the wood. My Maple is Balkan hard Maple, and it is brighter (white). Here are some pictures of the preparation of the headstock and neck for gluing: