That's a major repair for an amateur, but a professional would have to consider the cost. The correct repair is to replace the button.(Graft a new one on) that involves removing the back. Then replacing the neck or grafting on enough wood to re-shape the joint. whichever way the scroll should be saved. From your description this would probably outweigh the value of the fiddle. it might be possible to 'marry' up a new neck if you could find one but it can be tricky also.