u/moondustmamii

*DISCLAIMER*** long thread ahead** ⚠️

My sister moved in with me and my boyfriend about two years ago.
At the time, I was pregnant with our first child and my sister and I were really close. Her roommates were trying to upcharge her on rent and she didn’t really have anywhere else to go, so obviously I let her move in with us.
She’s always been the party type. She loves going out, drinking with her friends, coming home with some crazy story. I actually loved hearing about her nights out.
A couple months after she moved in, one night she came home drunk and I was the only one awake. We ended up sitting on the couch talking for hours.
Somewhere in that conversation, she admitted to me that she had slept with multiple friends’ boyfriends and even some of their husbands.
I remember judging her HARD in my head, but I laughed about it with her. She’s my little sister. I love her. I support her even when I don’t agree with what she’s doing.
But I never forgot that conversation.
And then I started noticing things.
Sometimes my sister and I would be getting ready in her room and she’d be changing. My boyfriend would try to come in and I’d tell him, “She’s literally naked, get out.”
And he’d still come in.
The first time he did it, he acted surprised.
“Oh shit.”
I brushed it off.
Then it happened again.
And then a third time.
And that’s when I started thinking, why are you so comfortable just walking into her room while she’s changing?
But I didn’t say anything.
Because what was I supposed to say?
“Hey, I think you might be attracted to my sister”?
I convinced myself I was being paranoid.
Then, about a month ago, I was doing laundry and found two pairs of my sister’s underwear in my basket.
I just stared at them for a second.
Then I told myself it was nothing.
We all lived together. Clothes get mixed up.
Whatever.
About a week later, I’m picking clothes up off the floor and I find my sister’s shirt and sandals.
She had worn that outfit the night before. I knew because she’d actually asked me if I thought her outfit was cute before she left.
My daughter and I had gone out that night and didn’t get home until around 2 AM.
And I remember looking at those clothes and thinking…
No.
Don’t go there.
That’s your sister.
But the thought was already there.
What if?
No.
She would never do that to me.
…would she?
The next day, I was rearranging my bedroom and had to move my mattress off the bed frame.
I slid the mattress forward.
And something caught my eye.
I reached down between the mattress and the headboard.
It was my sister’s pants.
The exact pants she’d been wearing the night before.
And then I saw her thong.
I just stood there.
I don’t even know how long.
Because suddenly every weird little thing I’d ignored started playing in my head at once.
The underwear.
The clothes.
Him walking into her room.
Every time they’d been alone together.
And I remember thinking, How could they even do this?
In my house?
While I’m here?
My boyfriend was out of town for work at the time, and my sister had just left for the weekend to stay with her best friend.
I wanted to confront them.
But then I thought…
No.
I needed to know.
So I decided to set them up.
The morning before my boyfriend got home, I told him I was going out to eat with my mom and daughter and wouldn’t be home.
He said that was fine and that he’d probably shower and rest when he got back.
My daughter was already staying with her grandma that night.
Everything was basically perfect.
Then, as I was leaving, I saw my sister pulling into the driveway.
She honked at me and rolled her window down.
I swear I had to act completely normal.
I asked her how her weekend was.
She told me all about it, then asked where I was going.
I told her I was going out with my mom.
She said she’d come, but she was hungover and wanted to go inside and take a nap.
I smiled.
“Okay.”
But inside I was thinking, please don’t.
A couple hours later, my boyfriend texted me.
“I’m home.”
I told him I was still out.
Then I left my mom’s.
The drive home was only about 30 minutes.
It felt like three hours.
I kept thinking maybe I was wrong.
Maybe I was about to ruin everything over nothing.
Then I turned onto our street.
And I saw both cars.
My boyfriend’s.
And my sister’s.
I didn’t pull into the driveway.
I parked a few houses down.
I walked up to the house and tried the front door.
Locked.
My heart was pounding so hard.
I took out my key, unlocked the door and quietly walked inside.
Our rooms were upstairs.
I started walking up the stairs as quietly as I could.
Thank God our stairs were carpeted.
I got to my bedroom door.
And stopped.
I could hear them.
I don’t even know how to explain that feeling.
All the sadness I’d been holding onto suddenly turned into anger.
I opened the door.
And there they were.
My sister.
My boyfriend.
Naked.
Together.
I completely lost it.
My parents had to be called because things got so bad they had to separate me from them.
I left that same night.
I haven’t spoken to my sister since.
My ex has begged and begged for his family back, but I don’t care anymore. The only relationship I have with him now is coparenting our daughter.
We have a court date next month for custody.
And honestly?
The part that hurts the most isn’t even that they slept together.
It’s that I trusted both of them.
I let my sister move into my home.
I trusted my boyfriend.
I was pregnant with his child.
And apparently, the two people I trusted most were the exact two people I needed to worry about.
I still replay that night in my head sometimes.
Especially the moment I opened that door.
I don’t think I’ll ever forget it.
Would you have done what i did?