I think that's "None Before Me" by Sidney Carroll. However, Carroll's story is told mostly in chronological order: we meet this reclusive rich collector (Mr. Gresham); he buys this magnificent doll house; he gradually becomes obsessed with it; in the end he goes completely mad and thinks the dolls are real people and he's their god.
The change from benevolent to vindictive god grew with his growing realization of the absolute power he possessed. Up till now he had been charmed by his playthings and had acted like a father to an adopted family. Now, when the father became the heavenly father, he indulged himself in his omniscience. When the children weren't looking he stole toys from the playroom. He hid them in the kitchen. One day he took the knitting needles from the grandmother's hands. "Enough damn knitting!" he stormed at her. "Try working for a living! Sweat of your brow!" He took her, rocking chair and all, and dumped her in the kitchen. He even attacked the swan crib and the sleeping infant. He knocked the crib over and the infant came tumbling out, rolling over and over on the floor. "Train 'em young," said Gresham. "Teach 'em life's full of hard knocks." He let the infant lay on the floor for two days. He pretended to pay no attention to the wailing sound he heard.
Then there's a flash-forward to the police investigation of Gresham's death,
They found Gresham later in a pool of blood, his head cracked in places like an egg tapped with a spoon. The glass of the window in the den had been smashed to bits.
The theory of the police was that Gresham had climbed to the window sill in order to throw himself out the window. That, being a fat and awkward man, he had bumped into the glass, shattering it. That he had then suffered some sort of attack, or had tripped, and had fallen over backward on his head. That was the way the police figured it out. But Gresham himself would have told them a different story about what happened that night.
He could have told them that he had had an extremely trying day with his flock. Nobody would stand up correctly. The furniture didn't look right. The baby wouldn't go to sleep. "Damn it!" he had screamed. "Shut up! All of you! Do as I say or--or--damn it, you'll roast in hell!"
followed by a flashback to Gresham smashing the doll house and being killed by a hand from the sky.
It was the back of Gresham's hand that had smote the building. Now the knuckles were bleeding. The hand was at his side and the blood dripped to the floor. "You fools," he shouted. "Never heard of a Day of Judgment? Wouldn't believe me when I warned you? The power of life is the power of death! I warned you—"
He raised the wounded hand and looked at it. The blood ran down his forearm. "Wash you in the blood—I'll wash you in the blood—you stupid, selfish, disobedient—people!"
He stood over the rubble and shouted, and exulted, and sweated. God—even a god—can not be entirely calm after producing an earthquake. Gresham could not keep his arms from shaking. But he knew he could go to sleep now. The evildoers had been slaughtered, vengeance had been wrought.
But first he walked to the window—first he wanted, for some strange reason, a look at the night sky. He walked to the window and leaned heavily upon the sill. He was still breathing hard, his throat and his brain felt curiously congested. He climbed up on the broad sill, as if, by getting close to the window, he could suck in more air. He stood there on the sill, leaning his full weight against the window, panting hard. He looked up at the sky. It was the faintest pale blue of the very early dawn. Not a single cloud floated up there--nothing . . . till Gresham saw. From the immense void, covering half the shoulder of the sky, the back of an enormous Hand was coming down at him--swiftly, powerfully, vengefully.
You could have read it in the anthology The Supernatural in Fiction (Leo P. Kelley, ed.) or in the Ray Bradbury-edited anthology Timeless Stories for Today and Tomorrow. Does any of these covers look familiar?