"The Hole on the Corner", a short story by the great R. A. Lafferty; first published in Damon Knight's anthology Orbit 2, reprinted in Lafferty's collection Nine Hundred Grandmothers and elsewhere. Does any of these covers ring a bell?
A housewife realised her husband wasn't her husband anymore, he had the same name and acted the same but was an ogre, when leaving for work he popped her entire head in his mouth for goodbye kiss. She was like "wow!"
Not leaving for work, he's just come home from work:
"Did you remember to bring what I asked you to bring this morning, Homer?" the loving wife Regina inquired.
"What did you ask me to bring this morning, quick-heat blueberry biscuit of my heart?" Homer asked.
"If I'd remembered, I'd have phrased it different when I asked you if you remembered," Regina explained. "But I know I told you to bring something, old ketchup of my soul. Homer! Look at me, Homer! You look different tonight! DIFFERENT!! You're not my Homer, are you! Help! Help! There's a monster in my house!! Help, help! Shriek!"
"It's always nice to be married to a wife who doesn't understand you," Homer said. He enfolded her affectionately, bore her down, trod on her with large friendly hooves, and began (as it seemed) to devour her.
"Where'd you get the monster, mama?" son Robert asked as he came in. "What's he got your whole head in his mouth for? Can I have one of the apples in the kitchen? What's he going to do, kill you, mama?"
"Shriek, shriek," said mama Regina. "Just one apple, Robert, there's just enough to go around. Yes, I think he's going to kill me. Shriek!"
Son Robert got an apple and went outdoors.
Some man works it out that the walls between dimensions have shifted and (not sure on this point) that it will settle down again.
The man who knew everything was named Diogenes Pontifex. He lived next door to Homer Hoose, and they found him in his back yard wrestling with his anaconda.
"Diogenes, come over to Homer's with us," Dr. Corte insisted. "We've got a couple of questions that might be too much even for you."
[. . .]
"I was first a gestalt two. Now I'm a gestalt three for a while," said Diogenes. Well, first we have the true case that a hundred or so solid and weighty bodies are occupying the same space that our earth occupies, and at the same time. This in itself does violence to conventional physics. But now let us consider the characteristics of all these cohabiting bodies. Are they occupied and peopled? Will it then mean that a hundred or so persons are occupying at all times the same space that each person occupies? Might not this idea do violence to conventional psychology? Well, I have proved that there are at least eight other persons occupying the same space occupied by each of us, and I have scarcely begun proving. Stark White Sycamore Branches! New-Harrowed Earth! (New harrow, old earth.) Cow Dung Between Your Toes in July! Pitchers'-Mound Clay in the Old Three-Eye League! Sparrow Hawks in August!"
He gets home and is like reading evening newspaper or work papers while his wife busies about the house. Then he really studies her as they make small talk and he suddenly screams. She is his wife but also a giant spider, he screams her name as she grabs him, she calmly tells him that (her name I forget) is her species name, and then she breaks all his limbs for easy handling.
"Then it's all right," Homer said. "I was just daydreaming on my way home, and all that stuff never happened. Here I am in the perfect house with my wife Regina, and the kids'll be underfoot in just a second. I never realized how wonderful it was. AHHHHNNN!! YOU'RE NOT REGINA!!"
"But of course I am, Homer. Lycosa Regina is my species name. Well, come, come, you know how I enjoy our evenings together."
She picked him up, lovingly broke his arms and legs for easier handling, spread him out on the floor, and began to devour him.
"No, no, you're not Regina," Homer sobbed. "You look just like her but you also look like a giant monstrous arachnid. Dr. Corte was right, we got to fix that hole on the corner."
"That Dr. Corte doesn't know what he's talking about," Regina munched. "He says I'm a compulsive eater."
The story ends with her eating him from the feet up while he goes "shriek, shriek, shriek".........that was the final line.
"Help, help," said Homer as she ate him clear up to his head. "Shriek, shriek!"