Should I pay for everyone's share of my birthday/leaving meal?

So, 2nd of Feb was my birthday and I moved to Scotland from London yesterday on the 3rd of Feb. A friend told me I should organise a celebration before I go and so I booked a restaurant for the 1st of feb and paid a deposit for 15 people, 3 of whom dropped out last minute, despite me asking multiple times for a decent amount of time for cancellations so I could find replacements, oh well, bad friends - lesson learned, I knew I would have to pay for their meals as they didn’t even offer to pay towards it even though I checked repeatedly and told people multiple times I’d lose money if they did this.

Anyway, I said it would be £25 pp and the restaurant bring out a buffet (I sent screenshots of the set menu) and you bring your own booze, I also paid a corkage fee for everyone on top of this which added an extra £45 to my bill but I felt rude asking for more money for that so I just took the hit.

It comes to the day of the meal and I had to pay for the whole bill as the restaurant wouldn't split it. In addition to this, the owner was very rude to me after I asked if we were having tea after the meal - last time I went they did this and brought us baklava too so I was curious if it was happening again and I asked in a polite manner as that is what I assumed was the deal. So ,I did ask for service charge to be removed as he had made me very uncomfortable in front of the whole party (if he'd been polite back I wouldn't have removed the service even though £25 each was a lot of money for what we got anyway). The next day, I thanked everyone for coming and put my details in the group chat, half of the people didn't pay. I felt bad because we're in our 20s and £25 each is a lot but also equally I double checked with everyone individually if they wanted to come before confirming with the restaurant (after making it clear it would be pay for yourself) and they all said yes. Also I am 25 with a minimum wage job. I wouldn't have minded if they said they couldn't afford it and that they wouldn't come, but this now means I am £300 down and had to use my entire birthday money gift and more (I got £100 from my grandparents, but I don't really get birthday presents from anyone else in my family) to pay for it, if I'd known this would happen I wouldn't have invited so many people as I was hoping to put that towards a sewing machine.

Is this my own fault and should I have just expected to pay for everyone? I feel uncomfortable and guilty asking people to pay again.

TLDR: My birthday/leaving meal, half the party didn't chip into the final bill and I had to pay for it