AITA for kicking my sister out of my daughter’s birthday party after she ruined the birthday cake on purpose?

I (32F) told my sister (29F) that she’s no longer welcome in my house after what she did to my daughter’s birthday cake, and now my entire family thinks I overreacted.

For context, my younger sister, “Lena,” has always had this weird need to be the center of attention. Growing up, if I got praised for something, she’d suddenly have a bigger accomplishment. If it was my birthday, she’d somehow create drama before the candles were lit. My parents always brushed it off with, “That’s just how Lena is.”

I moved out at 19 and honestly kept some distance for years because dealing with her was exhausting. But after I had my daughter, Mia (7), I tried harder to reconnect because I wanted Mia to know her family.

Now, Mia is obsessed with dinosaurs. Not princesses. Not unicorns. Dinosaurs. She spent MONTHS talking about this birthday party. I saved up to get this huge custom cake shaped like a T-Rex with edible volcanoes and little fossil details. It cost way more than I’d like to admit, but Mia had never asked for much, and seeing her excited made it worth it.

The party was last Saturday at my house. Everything was going perfectly. Mia was running around with her little dinosaur tail on, screaming “RAWR” at everyone. Kids were laughing. My husband was grilling burgers outside. It honestly felt like one of those rare moments where life is just… good.

Then Lena arrived.

Forty-five minutes late.

Wearing this skin-tight white dress that honestly looked more appropriate for a nightclub than a child’s birthday party. Whatever. I ignored it. I greeted her politely, offered her food, tried to keep the peace.

But right away she started making comments.

“Oh wow, this is… a lot for a kid’s party.”

“You spent HOW much on a cake?”

“When I was little we just had sheet cake and survived.”

I laughed it off because I didn’t want tension in front of the kids.

Then came cake time.

Everyone gathered around while Mia practically vibrated with excitement. The candles were lit, everyone started singing, and Mia looked SO happy she was tearing up.

Right as my husband handed her the knife to cut the cake…

Lena suddenly goes, “WAIT! Nobody move!”

And before anyone understood what she was doing, she shoved her finger straight into the side of the cake and scooped out a huge chunk of frosting.

The room went silent.

I’m not exaggerating when I say you could literally hear kids stop chewing.

Mia just stared at the cake like someone had killed her pet.

Then Lena laughed and said, “What? Someone had to ruin the perfection before the internet moms got their photos.”

Nobody laughed.

Not one person.

My daughter’s eyes filled with tears immediately. She asked, in this tiny voice, “Why would you do that?”

And Lena — a grown 29-year-old woman — rolled her eyes and said, “Oh my god, it’s just cake.”

At that point I snapped.

I told her, “Get out.”

She laughed at first because I think she genuinely thought I was joking.

I repeated myself louder and told her to leave my house immediately.

Then SHE got angry.

She started yelling that I was “humiliating her” in front of everyone over “dessert.” My mom jumped in saying I was escalating things and should “calm down.” My dad said Mia needed to “learn not to be spoiled.”

That made me even angrier because my daughter was literally crying while a room full of adults defended the person who upset her.

So I told all of them they could leave too.

And they did.

The rest of the party was awkward after that, but Mia eventually calmed down after my husband carefully repaired the cake as best he could. One of the other moms even helped patch the frosting while distracting the kids with games.

Later that night, my phone exploded.

My parents accused me of “destroying the family over a joke.”

Lena posted on Facebook about how “certain people care more about appearances than family.”

One cousin messaged me saying I should apologize because Lena has “always struggled with feeling second place.”

But honestly? I don’t care anymore.

Because here’s the part that keeps replaying in my head:

When Mia asked why her aunt ruined her cake, Lena didn’t look guilty. She looked annoyed that a seven-year-old was upset.

That’s what really got me.

Now half my family is refusing to speak to me unless I apologize for “overreacting” and “kicking out guests.” My husband says I did the right thing, but the constant messages are starting to get to me.

AITA?