I exposed him on stage at our engagement party

AITA for exposing my fiance affair at our own engagement party. I am going to tell this exactly how it happened because I still cannot believe I lived through it. My name does not matter here but my fiance name is Derek. We had been together for four years and engaged for six months. The engagement party was supposed to be the happiest night of my life. My parents spent thousands of dollars renting a beautiful venue with string lights and a live band. All our friends and family were there dressed in their best clothes. Everything felt perfect until I went looking for Derek because it was time for our toast. I could not find him anywhere near the dance floor or the bar. A strange feeling crept into my stomach so I walked toward the back hallway near the coat room. That is when I heard his voice through a slightly open door. He was laughing in that low voice he only used with me. I pushed the door open slowly and my whole world tilted. Derek was standing there with his hands on the waist of my own maid of honor, Sasha. Sasha had been my best friend since middle school. They both froze when they saw me standing in the doorway. Derek immediately stepped back and said it was not what it looked like. Sasha just stood there with her lipstick smudged and said nothing at all. I felt my heart pounding so hard I thought everyone in the building could hear it. I wanted to scream but something inside me stayed eerily calm. I told them both to follow me back to the main room because I had an announcement to make. Derek looked confused but relieved because he thought I was going to keep quiet for the sake of the party. He did not know me at all. I walked up to the small stage where the band had just finished playing. I took the microphone from the singer and tapped it twice to get everyone attention. The room went quiet and everyone turned to look at me with excited smiles, thinking I was about to give a sweet toast. I looked at my mother, my father, and all our friends sitting at their tables. Then I said that I had just found my fiance in the back hallway with his hands on my maid of honor. Gasps rippled through the crowd like a wave. Someone dropped a glass and it shattered on the floor. Derek tried to grab the microphone from me but I stepped back and kept talking. I told everyone that I had spent four years loving a man who could not keep his hands off my best friend on the night we were supposed to celebrate our future together. Sasha ran out of the room crying while covering her face with her hands. Derek stood there frozen, his face pale under the string lights. My mother started crying at our table while my father stood up looking like he wanted to punch someone. I took off my engagement ring right there on the stage and set it gently on the small table beside the band equipment. Then I walked straight out of the venue without looking back at anyone. The next morning my phone was flooded with messages. Some people said I was heroic for exposing him in front of everyone. Others said I embarrassed my own family and ruined an expensive party over something I should have handled privately. My own aunt texted me saying I should have waited until the next day to confront him quietly instead of humiliating everyone at the party. Derek later sent me a long message claiming Sasha kissed him first and he pushed her away, but I did not believe a single word of it because I had seen his hands with my own eyes. Sasha blocked me on every platform and has not spoken to me since that night. My parents lost the deposit money on the venue because the night ended early after my announcement. Some relatives still bring it up at family gatherings, saying I should have shown more restraint in front of guests. I keep asking myself if I destroyed my own credibility by making it public instead of leaving quietly with dignity. of me still feels justified because everyone deserved to know the truth before toasting to a fake engagement. But another part of me wonders if I gave Derek and Sasha the attention they secretly wanted by turning it into a spectacle. So tell me honestly, was I wrong for exposing them in front of everyone instead of handling it quietly.