This is gonna be a kinda vague apology, since I don't want EVERYTHING out there, if anyone's comfortable messaging me then feel free to and I'll be more direct and personal, you all should be unblocked.

In regards to 2019 + 2020-21: 
Especially in 2019 because wow, I had no fucking social awareness or respect of others' boundaries and feelings. I am genuinely so sorry for causing so much pain and stress on everyone around me, I was an extremely selfish person and only ever saw my own suffering instead of considering other's suffering. I was 14, I was a kid, an undiagnosed mentally ill kid, but regardless I should have listened to other's when they brought up issues about me (everyone around me was of similar age and had similar if not worse personal problems, so it's definitely not an excuse). I shouldn't have fucking publically trauma dumped or been so self centered. I apologized at the time, but it was so immediately after everything happened I can't blame others for not trusting it. I was cruel to my friends and people who cared for me, and I am deeply sorry. I blocked out a lot from that time, but since I knew there was still resentment towards me in 2020-2021, I can figure I caused a lot of harm.
I don't want there to be any lingering resentment, I don't want you all to still think of me as that abusive, selfish 14 yr old who still hurts others. I'm no longer that, I'm 19 now and have been making a lot more steps to heal from my own trauma and be a better person for those around me. I'm educating myself more on being aware of other's feelings (because autism does not let me do that automatically unfortunately, it's something I've had to intentionally learn-) and not being a selfish dick.
Obviously I don't expect any forgiveness, especially with how old all this conflict is I assume(?) everyone's moved on at this point. If anyone still hates me that is perfectly valid, just keep me blocked and don't stalk me please.

In regards to 2021-2022:
This was the first artist friend group I had after 2019, I've never been great at managing relationships due to my selfishness and poor social skills. It was also particularly awkward since there were also people I knew from 2019 in the new group, yet I just acted like nothing really happened?? I should've apologized right then and there but I was incredibly anxious and just wanted to pretend like everything was ok. Some conflicts happened between my old and new friends, and I ended up siding with my new friends. I don't agree with that decision anymore, as much as I understood my new friend's hurt, I don't believe I should've treated my old friends so coldly, especially since they were trying to be friendly back to me and me just cutting them off so abruptly is inexcusable from my part.
A major conflict happened as well, which caused my new friend to believe an old friend of mine was abusive towards them. Again I sided with my new friend, but mostly because the old friend didn't like me. Now-a-days I figure the old friend was having their own issues and just projecting it onto me and my past, but at the time I took it too personal.
Even though I know what I did in 2019 was shitty on my part, I was upset that my ex friends were still upset at me 2-3 years later (even though it's well within their rights to not like me) especially when I found out they were buying designs of mine, redesigning them and removing the credit. This was extremely hypocritical on my part as I literally did the same towards their designs, and I have now since added credit back to those designs. I was selfish and just wanted to pretend like nothing happened or that it "wasn't that bad" instead of just owning up to my fuck-ups and accepting the consequences of my actions, and I do apologize for acting so entitled.
I was still struggling with my mental illnesses during all this, and it affected how I viewed my new friends. I took every little slight personal and felt like I didn't belong, so I withdrew from them a lot, and mainly stuck close to my (at the time) best friend.

In regards to a specific ex friend:
I've contemplated on how to process this friendship for 2 years now, there's more details in this section since it's more fresh in my mind.
I've realized now it was a very unhealthy friendship, we were both incredibly mentally ill and codependent on each other. I never had a best friend or close relationship up until this point, and just wanted to stick by their side no matter what. I took their side on any conflict they had with others and would hate whoever they hated. We would text all day and it kept me going. I supported them on a lot of their personal issues and was always there for them, we were very close and cared for each other deeply. I cared for them genuinely and I still do. But I was still struggling immensely with my mental illnesses, and it affected my ability to care for them properly. I felt it was my job to give all my attention and focus on them, because they had no one else. They never asked me for this, i should note, but I just wanted to be someone they could trust and feel comfortable around.
I ended up betraying this trust, one day they snapped very harshly at me. Even though I knew it was their illness talking and not them, I was too scared and didn't know how to handle the conflict. I knew I did nothing wrong to trigger their outburst, and I tried reassuring them that I wasn't replacing them. They sent me a very long message with a lot of contradicting statements and sentiments, and it truthfully scared me. I wanted to help them but I didn't want to get myself hurt in the process. I didn't want to apologize for something I didn't do. I confided in someone I thought I trusted (though now I realized he has always abused me) and he pushed me to cut off all contact and block my friend. He insinuated my friend was abusing me and I believed him as I had no idea what else to think. I tried giving my friend a chance to cool down but they were strong on their stance so I ended up running away, I was too scared to have a deeper conversation.
This was incredibly fucked up of me to do, I was just too scared of getting hurt. I was scared if I gave into their beliefs this situation would happen again and that their insecurity would end up breaking up my relationship with my partner. I deeply regret what how I handled this and would give anything to change what I did, but I can't and my actions have caused irreparable harm. I've never gotten over it and it eats me up at times.
I always cared for you and never wanted this happen, I let myself get manipulated by someone who actually abused me. I never saw you as abusive, I know you didn't mean any harm, yet I still fled like a coward and for that I'm extremely sorry. All i wish is the best for you and for you to be able to heal from all the shit you've had to put up with in your life. I know this apology will seem ingenuine as it's 2 years late, and I'm very aware you hate me for abandoning you, and I completely understand. Just please know I never had any malicious intent, I never wanted to hurt you, I never wanted to leave you, and I especially never hated you. None of that excuses the harm I've caused, I know, but I still need to put it out there. I wish I could've met you when I was in a healthier stage of my life, as all i ever wanted was to help and care for you. I'm sorry.