Panicking, Cousin wedding date same month date 13 days away from mine

I'm really freaking out and can't sleep. I put a hold on my date for Oct 8th 2023 in January. And the following day found out my 1st cousin put his date in for Oct 21st 2023 and he's making the fam drive 3 hours. My whole life I've dreamed of an October wedding. I'm older for a bride (34 avg bride is like 28-32) and it took me some time to find my guy but him and I have talked about an October wedding for a couple years now because we just knew. After I found out about my cousin booked his date I rushed around to different venues(13) trying to find someplace closer to our families and a different date. Hindsight says I should've called him sooner but I didn't because the venue hunting was a struggle with dates flying off the shelf next year due to covid and the wedding boom. Plus my parents made it really difficult by being negative everywhere we went. We have put this off way longer than we anticipated and we need to pull the trigger like yesterday. I called my cousin today and he flipped out. I'm heartbroken. I don't know how to handle this and as it is my first cousin on my dads side I know my dad is going to side with him (which yes I know- hes like that- cares more about everybody else but not his own). I totally understand why my cousin is upset its why I gave him a courtesy call and told him my dilemma and that I really want to keep my date. At first he was fine then not 20 mins after started texting me to tell me I was being completely inconsiderate. Wouldn't even talk to me on the phone 😑. When I told him I needed time that evening to process emotionally his asking me to move it to another month he continued to get worked up and texting me nonstop until I told him I was shutting my phone down. My fiances family and my sister are telling me not to move it but I don't know what to do. I'm a so burnt out from venue shopping and a complete mess right now 😪😪😪