AITA for cancelling my daughter's wedding after finding out she's adopted (practices included)

I am, or should I say was supposed to be, the father of the bride this weekend. It is with a sad, sad heart and a heavy sore head that I regret to inform you that the wedding has been called off. I got married to my wonderful wife Sarah 34 years ago, and we had our daughter Laura 27 years ago. We have been good friends, you could say best friends for years. Sarah sadly passed away 13 years ago, it was a shock to us all. My relationship with my daughter became even closer then. <br><br>Laura found the love of her life and she told me she wanted to marry, I was over the moon for her. I met her partner and we got on well. They wanted to get married as soon as possible, so they could start their new life together. I am a very wealthy man so I spared no expense on this wedding. The wedding was to be a fairytale, castle, the works. I wanted my little girl to have her dream wedding. They chose to do some unusual things for this wedding however, they made some unusual requests. They wanted my daughter Laura to be flower girl, and her fiancé to be the groom. I was obviously confused when they told me. I asked if they were being serious. They told me they actually wanted my daughter to be the flower girl, and her fiancé to be the groom, it was a joke and they laughed about it. I thought it was a funny joke, but she told me it was not a joke. She was being completely serious. She was going to be the flower girl, and her fiancé was going to be the groom. I was gobsmacked. A grown 27 year old woman wanted to be flower girl at her wedding? I asked her what kind of sick game she was playing. This was not a joke to be making. They then started talking about a trolley and some kind of race, I was lost. I had never heard of such a thing. Laura started screaming at me that this was what she wanted for her wedding, she was going to be the flower girl and she was going to race her trolley down the aisle. I cannot lie, I slapped her. I never once raised my hand to her in her life, but this was too much. She was being absolutely bat shit insane. <br><br>The wedding was back on.<br><br>After the incident, Laura started making more and more absurd requests. She wanted to walk down the aisle with a ladder, she wanted to fill the fountain with gravy, she wanted to spin around in a circle during the meal. I finally snapped and told her enough was enough. We needed to go and see a doctor as she was going insane. She told me that she was completely sane, and that she just wanted a fun wedding. I asked her what she thought was fun about the wedding she had planned. She told me it would be hilarious. I asked why it would be hilarious. She told me that she could not tell me, and she was being completely serious. This was not a joke anymore. <br><br>The wedding was off.<br><br>My daughter was heartbroken, she moved in with her fiancé. I was devastated. I had never been so heartbroken in my life. My little girl was gone. <br><br>I started to get suspicious, something was not right. There was more to the story than what I was being told. I received a call from a lawyer a couple of days ago. Laura had hired a lawyer and was going to sue me for money. I laughed down the phone. I told him that Laura was my daughter, so she was entitled to half my fortune anyway. He paused and told me that his client was not entitled to any of my fortune. I was confused, if Laura is my daughter, then surely she is entitled to my fortune. The lawyer then told me that Laura was not my daughter, and then hung up. I immediately called my wife, but she did not answer, she had died 13 years ago. Not knowing what else to do, I called my brother. When he answered, I immediately asked him if Laura was my daughter. He told me that Laura was in fact my niece. A few years before Laura was born, my sister (Laura's mother) and her husband had a still birth. They were devastated by the loss of their baby girl. A few years later, my wife gave birth to my beautiful daughter Laura. A year after that, my wife gave birth to a still born baby girl. We were devastated, we decided to cremate her and tell no one what had really happened, and to pretend that she had been born healthy, and that Laura was in fact our still born daughter. Laura was then sent to live with my sister and her husband, and their still born daughter was passed off as mine and my wife's. I asked my brother if this was true, and he said it was. They had kept this a secret since before Laura was born. I asked him why they would do such a thing. He told me they did not want to upset anyone. I asked why they had decided to tell Laura. They had never planned to, but my sister and her husband had died a few years ago, and Laura had found some documents that revealed she was adopted. She had hired a Private Investigator, and he had found out the whole story. <br><br>I am struggling to cope with this new information. I do not know what to think, or where to turn. The wedding is off, and I am left to pick up the pieces of my life. <br><br>AITA for cancelling my daughter's wedding after finding out she was adopted? <br><br>EDIT: I have seen a few people posting that this could not happen in real life. It has not happened to me in real life. This is just a fictional story I made up. It is not real.