One time when I was in 8th grade and my sister was in 5th grade, we found the old easy-bake oven my dad bought nearly 10 years earlier. My sister pulled it out and check the ingredients that said they expired in 3 months. So she decided to go ahead and make them that day.
I was sitting at the kitchen table, next to the easy-bake oven, doing my homework when the phone rings. My sister goes to answer it in the other room.
I get up to go put my finished homework away when I accidentally trip over the easy-bake cord. There was a small pan of unbaked liquid inside the oven that spilled on the lightbulb inside, causing it burn out.
My sister was completely okay with it, it was an old device and we weren't going to use it after that to be completely honest. But we still thought it was appropriate to tell our mom.
This is where things went wrong. We go into her room and tell her. "WHAT!?" She comes out, looks at the device and tries to figure out if unplugging and plugging it back in works (spoiler, it didn't).
Then she got mad.
"WHY'D YOU DO IT, HUH?!? YOU DON'T LIKE YOUR SISTER?! YOU BETTER ANSWER ME!!"
And I'm a timid 8th grader. So her screaming doesn't help me answer any quicker. But eventually, when she let me get a word in, I told her it was an accident, I didn't see it there.
"BUCKSHIT, YOU COULDN'T STAND TO SEE YOUR SISTER HAPPY SO YOU BROKE IT, DIDN'T YOU?"
This went on for about 2 minutes, me repeating my stance that it was an accident and he calling me a liar until she got mad and said, "I'm going to ask you again, and don't give me the excuse, 'It was an accident' because that's not going to fly. Why did you break it?"
And now tears are rolling down my face, I'm scared she gonna whoop me or something and I don't know what to say. So I just say, "I don't know."
"I don't know is not an answer. Why did you do it?"
This went on 3-4 more times before I said I don't know again and she goes Bruce Banner, grabs the easy bake oven, and throws it hard on the floor, popping off the back of the oven and shattering the burnt out bulb. She then looks at the bulb and says, "Look what you did when you decided to fuck with your sister's shit. You shattered the bulb."
She orders my sister to go get my ebook from my room, another thing my dad, not her, bought, and to throw it of the balcony to, "See how he likes having his shit broken."
Then she asks again why i did it, I said I don't know, and this cues the Benny Hill Theme Song scene where I'm running around the dinner table and she's chasing me with a screwdriver.
She gives up the chase and says, "Go pack your fucking bags, and don't even think about going to your Father's place."
I go to pack my bags, 10 minutes, my sister comes in and says, "Mom wants to see you."
I go into her room and not she's all apologetic and asking why I'm crying and I want to scream at her but instead I let out, "You scared me."
All of a sudden she's a Mother-Fucking-Model with her phony sympathy and I'm too scared and too young to even try to do anything about it.
So yeah, I'd say right around the time she pulled the screwdriver out, I'd say that's when I started to dislike her.