MAKE IT STOP!!!!!!!!!!

I am writing the short story that would not end. Will. Not. End. It's my own fault. I went into it with a premise I liked, but not a lot of structure. It took off on me and I'm having a great time with the characters and the dialogue, but I'm nearing 10,000 words and it's not ending.

My darling Andy pointed out that it might be helpful if I knew how I wanted it to end and I do think that's part of the problem. There's really only one good ending. The bad guy has to die. He's a threat that can never be neutralized. He's driven, he's got nothing to lose and he feels that he's on the side of the angels.

I don't think I can stand to kill him, though. I know what happened to him. I know the horror of it all. I know he's certain that he's out slaying the dragons that threaten all that's good and pure about our world. How can I kill him?

The problem is, how can I not kill him?

And so the story keeps going. Help me. Please.