AITA for refusing to go to my brother's wedding?

My fiancé "Mike" and I have been together for 5 years. We are thinking of getting married in 2024.<br><br>My brother and I are not close at all. For years I've tried to set up appointments, phone calls, just anything to get to know him better but he just never bothered and instead says it's my fault we're not close.<br><br>He's getting married next year and he asked me to be his best man. I was quite shocked about it and agreed as it might be a chance for us to become closer but then I found out that his wedding will be on the exact time and date that Mike and I are planning to get married.<br><br>I told him that but he said that it's too bad as he already booked the venue. I asked if he could change the venue so that we have more time to choose a different date but he said he can't.<br><br>I told my parents about it and they said that they will go to his wedding and that I should too. I told them that I will be getting married at that time but they said that I should postpone my wedding for my brother's as they don't want to choose between their sons.<br><br>I'm really lost here as my brother just said I could come to his wedding after it but my parents think it's the most terrible thing ever.