Broken over having to put my bunny to sleep

I had to put my bunny down 2 days ago and I can barely function. He was my best friend he saved me.
He had a bigger personality than ever imaginable and very smart, he was freeroam of course so he was always with me. He was very loving and he always listened to me though he did sometimes go against my rules such as trying to sneak a snack when I left the room lol. He was incredibly wellbehaved using his litterbox even before he was neutered and always running to the litterbox when he was in another room instead of peeing/pooping on the floor.
He was lovely and he didnt get very old. Rabbits are prey so they hide their illness often until its too late to save them... Its the big risk with having a rabbit. I was shocked and had to make that horrible decision. When I realized what I needed to do I broke down. I told him whats gonna happen and that I love him and I dont want him to suffer anymore. I then kept telling him how much I love him and what did he do? He reached up to my chest and licked it. His way of saying goodbye and that its okay.
I cant eat nor can I shower or do anything else. I guess only someone whos had a rabbit (and cared for it properly not stuck it in a cage which is animal cruelty by the way) would understand. I posted to a rabbit group and they understand of course, some even grieving years later and lighting a candle everyday for their lost one.
None of my friends seem to care though. Well tbf I dont really have any I guess but I have people I know/acquitances and 2 internet friends and only one of my internet friends has given condolences. My other friend says nothing which I find extra hurtful, ive helped that friend through a lot which he has always thanked me for but hes not there for me in a time like this. Guuess its show me my real friends and which people I do not need to bother caring about anymore.
I dont know how I will be able to work but I have to do my best. I have lost the light of my life and having to put him to sleep was traumatic and I feel constant guilt and I get flashbacks to him dying and to the last night I spent with him. You see he got sick around midnight. It started with him spraying pee everywhere and like every 5 minutes then he would whimper. He was still eating but eventually stopped because everytime he ate he started to whimper like it hurt when the food came down to his tummy, and then he would press out more pee. I had no way of getting to a vet until 9AM so I had to sit there and just hope he wouldnt go into seizures and die in agony. He had been completely fine all day, thats how well rabbits hide their illness.

The vet said his bladder was enlarged and he was in the brink of poisoning, he had a massive bladder stone blocking his urine. His abdomen was very bloated. The insurance did not even cover half of the extensive surgery he needed, and honestly I dont know if in that state he wouldve survived surgery... Its always a massive risk to give small pets anesthesia.
I just cant believe it. The nurse said stones like the one he had arent that common with rabbits, yet I was so strict with his diet that it sometimes annoyed my mother since I insisted on the highest quality pellets, hay from a local farm and keeping treats to a minimum. In the end no matter what I did he died very young, it is so unfair. 💔 I will never understand why this happened to him. 😞