AITA for Leaving My Fiancé After Finding Out He Was Secretly Dating My Best Friend for Almost a Year?

I’m 26F, and honestly, I still can’t believe this is my life right now.

Three weeks ago, I thought I was planning my dream wedding. Today, I’m back living in my childhood bedroom at my mom’s house, crying at random hours, questioning every memory from the last four years.

I met my fiancé when I was 22. He was sweet, calm, funny in a quiet way, and he made me feel safe. After a toxic relationship in college, he felt like peace. Everyone loved him — my family, my coworkers, even my friends.

Especially my best friend.

She and I had been friends since high school. She was the type of friend who knew everything about me. Every heartbreak, every insecurity, every dream. She stood beside me during the hardest years of my life. When my dad was in the hospital, she slept on the waiting room chair with me. When I got engaged, she cried harder than I did.

At least I thought those tears meant happiness.

Looking back now, I feel sick realizing how blind I was.

About a year ago, my fiancé started acting a little distant. Nothing huge at first. Just small things. He’d turn his phone over when messages came in. He started going to the gym late at night. Sometimes he’d take forever replying to me but somehow always had time to like my best friend’s posts within minutes.

I noticed it, but every time I questioned myself, I felt guilty. I didn’t want to become “that paranoid girlfriend.”

And honestly, they both made me feel crazy anytime I hinted something was off.

One night I jokingly asked, “Imagine if you two secretly liked each other.”

My best friend laughed SO hard she nearly spit out her drink. My fiancé looked offended and said, “That’s actually disgusting.”

I remember apologizing for even saying it.

That memory keeps replaying in my head now.

Two weeks before our wedding, my best friend suddenly started avoiding me. She claimed she was stressed from work. Meanwhile, my fiancé became weirdly affectionate. Buying flowers. Planning dates. Acting like the perfect man again.

I didn’t know it was guilt.

The truth came out completely by accident.

My fiancé left his Apple Watch at home while he was showering. It kept buzzing nonstop. I normally would never check his messages, but the screen lit up with her name followed by:

“I miss last night already.”

My stomach literally dropped.

At first, I convinced myself there had to be some explanation. Maybe I was misunderstanding. Maybe it was a joke.

Then more messages appeared.

Explicit ones.

Plans to meet.

Her complaining about me.

Him saying he only stayed because leaving before the wedding would “destroy everything financially.”

I can’t even describe what that felt like.

It was like my entire body went numb. I remember staring at the bathroom door while hearing him hum casually in the shower, and all I could think was:

“How can someone betray me this deeply and still act normal?”

When he came out, I just held up the watch.

The color drained from his face instantly.

At first he tried denying it. Then when he realized I had seen enough, he broke down crying and admitted they’d been together for almost a year.

A YEAR.

Do you know what hurts most? It wasn’t even just sex. It was emotional too. They had inside jokes. Secret trips. A whole relationship happening behind my back while I was planning a wedding.

And my best friend? The girl who helped me pick my wedding dress? She was sleeping with my fiancé after pretending to comfort me about “relationship stress.”

I completely lost it.

I screamed. I threw the engagement ring at him. I asked him over and over why he proposed if he loved someone else.

His answer destroyed me.

He said he “did” love me, but things with her “just happened.”

Just happened.

Like betrayal is some random weather event.

After that, I called my best friend. She cried immediately and kept saying she never meant for this to happen. She said they “fell in love” accidentally and were trying to figure out how to tell me.

But apparently not before the wedding deposits were paid.

I blocked both of them.

Now here’s why people are divided.

His family keeps contacting me saying I’m overreacting for canceling the wedding completely because “relationships are complicated.” My aunt even told me that “all men make mistakes” and throwing away four years is immature.

Meanwhile, some mutual friends think I should’ve at least heard them out because “real feelings developed.”

I feel like I’m going insane because how am I somehow being made to feel dramatic after being cheated on by the two people I trusted most?

I lost my fiancé, my best friend, several friendships, thousands of dollars in wedding deposits, and honestly a huge part of my ability to trust people.

But somehow THEY are acting like victims because I exposed the affair publicly after people kept asking why the wedding was canceled.

So… AITA for cutting them both off completely and posting the real reason online after they begged me to keep it private?