Peter followed the Green Goblin from the George Washington Bridge to the warehouse. However when he arrived he was hit with diamond spikes, creating three gashes across his chest, however the suit reformed over them and they stopped hurting.
"You really think I wouldn't expect you to come after me?" said the Goblin, "I killed your girlfriend for god's sake!"
"Yes," said Spider-Man, "and now you're gonna pay." He punched the Goblin square in the face. Teeth came flying out from both the mask and his real mouth. Spider-Man shot webs at the Goblin that stuck him straight to the wall. Spider-Man picked up the sharpest object he could find and swung it at the Green Goblin, cutting through both armor and skin thanks to his newly increased strength. He repeated this action at numerous points.
"You killed my girl! A human life!"
"Does it matter? Is all this worth it if it's over one insignificant female life?"
"You're talking about my lady, creep! Someone I loved! Do you know what that means? Have you any idea what that means? I loved her, Goblin! And you took her away! You filthy worm eating scum!" He was about to go for the heart when suddenly he came to his senses.
What am I doing? he thought, I'm not a killer. He put down the object. However instead of being shocked at what Spidey almost did to him, the Goblin was laughing,
"Hahahahaha, hahahahahaha! You just made the worst mistake a hero could make, you let your adversary live!" Badbat, who was behind Spider-Man, opened its mouth and extended its fangs. It flew toward Spider-Man, but at the last second his spider-sense warned him and he dodged the bat. The Goblin, stuck to the wall by Spidey's web, was impaled. The robot retracted its fangs, closed its mouth, landed, and shut down, though one fang got stuck and broke off.
"So do the proud men die." said Spider-Man over Osborn's corpse, "Crucified, not on a cross of gold, but on a stake of humble tin." Spider-Man thought seeing her killer die would make him feel better about Gwen, instead it just made him feel empty inside, and maybe, just a bit more alone.

(at this point in the movie the credits would play)

Peter swung through the city, wondering why he tried to kill the Goblin even though he normally wouldn't think of it. He pondered this until he noticed once again his suit was black. He then thought back to when it turned black and how everything changed then. His eyes looked baggy and almost jaundiced, his skin was pale white, he was acting all strange like an adrenaline junkie, and most recently he tried killing a man. He went to the church bell tower and tried removing the black ooze from his suit. He couldn't do it no matter how hard he tried. He was so frustrated he hit the bell. Then the sound of the bell made the ooze freak out and try to jump off. He hit the bell again and again, each whack giving him another window of opportunity to tear it off of him. After much struggling he managed to fully get it off of him. The stuff off his body looked significantly different than it did a few months ago in the container, it had a distorted web pattern to it and it moved more like a spider than an ooze. It was clearly weak, struggling just to move a couple feet. Peter would have felt sorry for it had it not almost made him kill a man. Peter soon realized he too was weak, struggling just to stand up. He collapsed on the floor.

(at this point the credits resume)

A man sat in the pew at a local church (his face is not shown).
"Dear Lord," he said, "I think my friend is having issues, issues I can't seem to help him with. So if You could help me help him I would greatly appreciate it, Amen." He heard a strange noise.
"Who's there?" he said. He looked around and could only see shadows. He was about to resume praying when he realized there was nothing to cast the shadows. The shadow began to creep towards him. He was enveloped in it. He collapsed down. His body was now coated with a mysterious black substance. It eventually assumed a shape, with a distorted web pattern in some areas and gray veins on some parts (in the movie those are the only parts we see of it and they're really up close, we don't see it in full).

THE END