Please let me know if I'm (18M) being TA or not.

To start with. I don't live with my dad and stepmom anymore. My best friend's mom let me move in with them when I turned 18 last month. This was a very last minute move and not one my "parents" approved of. They argued to keep me with them and when I mentioned in our fight that I don't live with them anymore they said that was a decision I made not them.

Anyway, moving onto the problem. I never knew my bio mom. According to dad she left when I was 2 weeks old and decided she didn't want to be a mom. She died just before my second birthday. This much I know is true because I have seen the obituary and what dad said does sorta make sense because it didn't mention me at all and only mentioned her family and friends. I was 3 when my dad met my stepmom and I was 4 when they got married. I think I called her mom right from the start.

I always knew my stepmom wasn't my real/bio mom. But she called me her son and said she was my mom so I saw her as the real deal. The thing is her family never wanted anyone to forget I wasn't her real kid. They did not treat me as a grandson, nephew or cousin. I was treated as less than. It got worse when my siblings were born. My stepmom's parents would ask her for photos of their grandbabies and that meant me not being in those photos.

My dad and stepmom never demanded I be treated equally. They would never stand up to anyone who said I wasn't a part of my stepmom's family. Nah, they'd act like it wasn't happening and they'd let me be pushed out. But I was expected to call her mom. Even when her family corrected me and said she wasn't my mom I was supposed to keep doing it. I was 8 when I first used her name instead of calling her mom and I got into deep shit when we got home. My dad told me I had made my "mom" cry and how could I break her heart like that.

One time when I was maybe 10 we were at my stepmom's parents house and their neighbors were there. They bought me an ice cream along with all the other kids there. My stepmom's mom actually took the ice cream cone out of my hand and tried to berate her neighbor for it, saying I was not a part of the party. Her neighbor (the lady neighbor) asked why I was there if I wasn't part of the party and she said I wasn't staying. The lady neighbor said she didn't care and she wouldn't feel right leaving me out. It got tense and my stepmom's mom told me to go sit down and not accept the ice cream. My dad and stepmom watched the whole thing happen and did nothing to defend me.

When I was 12 I had decided they weren't my parents if they could be like that and I stopped calling her mom and instead used her first name all the time. I called my dad father instead of dad because it sounds way colder to me and because he technically is my father. Like biologically and legally. But my stepmom never adopted me. I stopped telling people she was my mom and said stepmom. And I started saying they weren't my parents. They didn't like it and I was grounded, punished, had privileges taken away for doing it but I saw no reason to give them more than they gave me.

The breaking point for that had been a Disney vacation that I was excluded from. My stepmom took my siblings but had agreed not to take me because her family didn't want me. Dad went with and I was sent to my best friend's house for a week. They never paid my best friend's (single) mom for it either even though they said they would.

The fights got really bad in lockdown. And I would bring up my issues with them but they said I was blaming them for other people's actions. But when I asked if one of my siblings was treated the same as me would we see her family still, the answer was hell no before they backtracked.

The issue over me not calling them my parents is still an issue and now my graduation is happening in a month and they are not on the list. I gave my list a few days ago. Our school doesn't have much space for graduation so only people on the list can come. And when they realized they weren't on the list they called to complain. I ignored them but they left voice messages and then they showed up at my best friend's house to demand answers. They said I owed them better than all of this. I asked them why I should call them my parents, why they should get to see me graduate when they are fine with me not always being her son or family. I brought up how they stood by while that was said over and over again and did nothing to protect me. They told me that's me again punishing them for the actions of others and not their own. I said it was their actions. They said I expected them to deny everyone the only family there, to deny my siblings the only family they have, for my feelings. They said it was selfish.

I think it's them being shitty still but I wanted to check this with others. AITA?