I have a twin brother and I have always had a similar relationship with him. He is the golden child and social butterfly. He was also the boy that my parents seemed to desperately want. I got out of the Navy due to a suicide attempt. He told me that I have dishonored our family and he felt like he should join the military to bring honor back to our family. He however would never have the guts to join the military. Just mock me for doing it. Interestingly my dad being a con man and a felon would have dishonored our family years before. My parents both took his side pretty much our entire lives. If he hit me it was my fault, if he insulted me it was my fault. He was popular and a football player, now a football coach so therefore he is more successful than me, even though the other months out if the year he works a entry level job and moochies of his wife. I am a veteran with a college degree who works as a paralegal and supports myself but am not as good as him. I have tried to have a relationship with him for years lately I have realized that he has a very small opinion of me. He makes me feel like crap and claims the chronic pain I am in is in my head, any mental health issue I have is in my head, the men who sexual harrassed and assualted me in the Navy that was in my head.
So anyways to answer you question NTA sometimes it's better for everyone to cut contact if they really care about you they will make an attempt to contact you or maybe not be such an A hole to you. I have cut contact and my brother has not even noticed but I think it is better for my mental health to do so.