AITA for refusing to discuss my stepfather's will with my siblings and the fact I was right and he wasn't my dad?

The father of my siblings died 11 months ago. He had been married to my mom since I was 4 but he never considered me his kid or treated me like his own. He told me himself when I was a child that he was not my father and my daddy was some asshole who walked out on my mom when she told him she was pregnant with me. He said if I ever wanted a father I needed to track him down but I shouldn't expect him to step up. He wanted his own kids.

My mom and him had three kids together. There's an 8 to 11 year age gap between me and them. And they always believed we were full siblings. My mom never corrected it and their father never realized they believed that. When they were all 12 and older I sat them down and I told them we had different fathers. I had wanted to do it before but they were kind of petulant kids and I knew I'd be wasting my energy trying to convince them. Back when I did explain it I even showed them my birth certificate as proof. They didn't believe me and had all these excuses. When I pointed out the difference in how he treated us they said that was just because I was the oldest.

My mom died 5 years ago. Her husband became ill after her death and my siblings and I had a big fight because I refused to contribute to or help with the care of their father. They hated me for it and said I was taking the difference in treatment out on him when it was known older kids have it different. They told me if this was more he's not my dad bs then I needed to get the fuck over it and accept that we're full siblings.

Now that he's dead? They have finally accepted it because he left me nothing in his will and left very strict instructions that I get nothing because I'm not his child.

My siblings are in their 20s now and I'm in my 30s and I'm married with kids. It really doesn't bother me that he left me nothing. I knew from a young age to expect nothing. I had accepted that if he lived longer than mom that would be it for me. I cared for him as much as he cared for me and his death has made no difference to my life.

Now, after all the crap my siblings have thrown at me, they want us to talk about it. Not only that but the will. I refused. I told them I was not going to rehash all this again and they were free to discuss it with each other but since they didn't apologize to me yet I could assume didn't feel bad about it and I didn't need anymore fighting with them.

They accused me of never giving them a real chance to understand. I told them they had been so quick to shut down the truth and to accuse me of just being a petty daughter and unable to accept the truth because I was bitter that I didn't feel the need to give them more chances with this. I said I had accepted long ago that the man would have been happier if I didn't exist and wasn't around. I didn't need to hold their hand through the truth that's nothing to do with them in the end.

They think I should be more open. Maybe I should be. So I wanted to ask AITA?