AITAH for the way I called a friend out on their behaviour

this actually happened almost 2 years ago now but I've thought about it daily since and I would appreciate some impartial feedback because I've gotten dramatically different feedback from the other party and people close to me and I'm not sure who to listen to. I don't want to be in the wrong and be blissfully unaware of the fact but I don't want to be right and think something went wrong that I'm oblivious to either.

I've known this man since we were 7. we grew up together and spent most of our free time together so we were extremely familiar with each other and we were ~23 when this happened.

for the past ~2 years, I'd noticed a few behaviours I found concerning but I didn't bring up in the moment since I was hoping it was temporary like he was having an off-day or it was a one time thing or whatever but to me it looked a lot like some form of cognitive deterioration the longer it persisted.

I ended up trying to talk to him about this for a few months about this but he'd stopped responding at all so I assumed he was busy or needed space or just something along those lines so I would leave him alone for a while after each attempt but I was still there for him if he needed me. I'm autistic and struggle with social cues so maybe I just wasn't picking up on something like he was purposely ignoring/avoiding me. who knows. he never really gave any signs or said anything for me to think this was the case.

eventually I'd had enough of waiting because our friendship was taking it's toll on me and I needed to get this dealt with one way or another so one day I opened up with the line,

"hey [name] do you think things are ever gonna get better for you or is how you are now just sort of where it peaks".

I was hugely banking on the fact that we'd known each other for 15 years (we had a break at some point) and he'd know me well enough to know this wasn't meant to be mean spirited and that it was coming from a place of genuine concern, curiosity and care. I needed to address his behaviour and finally have a talk about it and I could not keep holding onto these thoughts any longer... you can probably tell from the buildup that this didn't go over well but I wouldn't find that out until way later through his other friend.

he asked where it was coming from > I said I had concerns > he asked what they were > I listed them but I made sure to hold back in an attempt to spare his feelings and get the lighter stuff out of the way

and then that was when he took it as an opportunity to lash out at me through "retaliation". he'd apparently been holding onto unflattering opinions and criticisms for years which felt insane considering I'd been open about accepting criticism to the point where I would openly invite it but yet we'd never had a serious talk regarding my behaviour, so to me that meant everything was just peachy keen.

this "retaliation" came out in the form of a dissertation 7 hours later, first thing in the morning, followed by a swift removal from everything we'd shared together or had each other added on (which btw was a lot). I wasn't sure how I was supposed to be taking or interpreting any of this so I'd taken the more serious stuff to my psychiatrist and requested an evaluation (I'd been told numerous times in the response that I'm a narcissist or at least have narcissistic tendencies) and was told I have literally zero signs of any kind of underlying personality disorder and that a lot of autistic traits can be confused with narcissistic ones purely due to miscommunication so honestly that felt like another dead end when it came to finding answers. other than that, I did try to take as many lessons from it as I could but when I'd repeated them to his other friend, I got told I'd lied to her in order to make myself look good... so again, I'm kind of at a loss.

I'm happy to share messages regarding this post from way back if I have to. this is my first post online outside of a comment or half baked tweet ever so I apologise for the messy structure and I just hope I did this right. I had to leave a few things out because I felt like the post might end up too long and I do remember trying to post this before but turned out there was a character limit. all the main events and details are here though.

I know I could've done some things better but AITAH for the way I handled this situation? I did my best at every point to be considerate and sensible with all the information I had