It’s a great feeling to finish a piece of writing. Triumphant. So looking at work you thought was finished and realising it isn’t finished at all is painnnnnnful. The mind goes in to self-defence mode. Or self destruct mode. Obviously you suck. What ever made you think you could write at all. Give it up. Anything, except the truth of the situation.
Yep. That needs another draft.
Swear a bit. Punch something inanimate. (Try not to break your hand though, you’re going to need it.) Have a stiff drink and / or a smoke. Then knuckle down and get writing, because what separates the professional and everyone else is the willingness to tear your writing apart and put it back together again, better, faster, stronger than it was before.
It’s going to be a long weekend.