AITAH for telling my boyfriend about my best friend’s kiss with him ?

I’ve been dating my Boyfriend for two years and everything seemed perfect until my best friend told me something shocking.

A few months ago, she confessed that she had kissed my boyfriend at a party before we started dating. She swore itt meant nothing, that they were both drunk, and that it was a mistake. But she was worried it would come out eventually and ruin my relationship if I found out later.

I was confused and angry but she begged me not to tell my boyfriend about it saying it would only cause unnecessary drama.

I spent days thinking about what to do. On one hand I wanted to trust my boyfriend and I didn’t want to destroy our relationship over something that happened before we were together. but On the other hand I felt betrayed by my best friend. Aftr much thought, I decided to confront him .

I told him what I knew and his response was cold. He admitted it happened but claimed it was before we were officially together, and it didn’t mean anything. He said he didn’t want me to know because he didn’t want to ruin our relationship.

I was furious, but after a long conversationn we agreed to move forward. However, the tension between my best friend and me grew. She kept insisting I should have never told him, that I was blowing it out of proportion, and that I was the one causing unnecessary drama. Now, my boyfriend is upset with her, and she is mad at me for breaking up their "friendship”

I can’t help but feel like I did the right thing, but now my relationship with both of them is in jeopardy. Am i the asshole ?