I ended my friendship with someone I thought to be very well with. The whole story took place at the beginning of september and I'd love to pretend I am over it, but since I am still thinking about it occaisonally, I can safely assume I do regret at least a tiny bit. 

We know each other for 3 years and have been together on several holoday trips. We were the kind of friends lurking around in the voice chat until deep into the night, talking about all the stupid things 16 to 19 year olds had on their mind. 

His birthday is on the beginning of september and he invites me for a small party with only 4 guests, all of our friendgroup. He didn't want to celebrate big this year he told me. 
However shortly after the invitation, I notice my friends, the ones invited along me to the small party, talking abour the big party on saturday. I was invite on friday though. 
Of course I curiously asked about the details. Turns out my friend is about to throw a big party on a playground with lots of alcohol and lots of guests the day after. He paired up with a girl he knew from school and overall round about 30 people were invited. 
What made me go crazy was the fact that everyone else from our friendgroup was invited, except for me, they were told to bring their girlfriends aswell. At that point I openly asked him, why I wasn't invited. I was told about there not being enough space (remind you 30ppl on a public playground!) and the others were "only" invited because of some kind of "chain invitation" person x because he knew y and  then z for x so he had more than one. I further questioned why I wasn't in his "chain", but he didn't answer. 

Anyways I went to the small party (I shouldn't have went there) and when I left I waved one final big ass red flag about the next day, asking when I should be there tomorrow. He smirked and he should have left it at that, instead he insulted me :" I am not going to invite you, but I won't send anyone home who shows up.".  
That pissed me off, I turned around without saying anything. 
Nevertheless he isn't done yet, the next evening he send me pictures via SC/Instagram etc about his party. I blocked him everywhere afterwards and muted him on Discord. 
Around that time our common friends tried to bring us back together, he was apparently admiting slight remorse to my friends, worse for me was however that none of my friends, who all were invited, understood my anger against him and played it down. The party was bad/boring but noone out of 5 guys could understand my position. I told all of them to stop trying to get us back together and after a while they  respected. 
The swing in the story is the birthdayparty of a common friend at the end of october.  We were both invited and I made sure to be polite with him, but cold. Inevitably he asked me for reunion later during the party, I reclined, I thought about what to say beforehand, because I wanted to "stay strong". 
The next morning I was talking with my mother about the party and mentioned howI stayed strong (note this is how i first viewed it, since my ego was scratched). She just asked me, wether I was sure and happy with my response.
Now it is the end of december and I still sometimes thing about my decision to recline. 
Therefore I decided to set up the post.

AITA?

Disclaimer: Not in the US, but Germany, hence public drinking not a problem.
Excuse the formating, I am writing on mobile. 