I don't know which forum is best, so I'm posting this here. If it's the wrong spot, apologies.

I am wondering if my sister is a psychopath. When we were little kids, she once told me, "sometimes I like seeing other people suffer". That stayed with me because I was disturbed by it. It also explained a lot of her behavior over the years.

She's a very selfish person. She would never share her snacks or toys. Whenever an adult gave us something, she'd take the bigger share. We are very close in age, so as kids we were small enough to wear each other's clothing. Whenever my mom would dress me in my sister's clothes, she'd throw a screaming fit, saying "I don't want her to wear my clothes!" However , if she wore my clothes she wouldn't protest. She has no sense of fairness or equality.

She would do cruel things to my brother and me. One time my brother did something wrong, and she told him unless he did what she wanted, she would tell our abusive father. She made him stand in an area of the house that had large roaches. She knew he was scared of them, and I think she wanted to wield power over him.

She has a grandiose sense of self worth. When she was in college, and after, she'd just show up for visits here without calling or telling us ahead of time. It was like she was playing a game with us. I got angry because she was in my space for weeks, and I had made plans she expected me to interrupt. She acted like I was being unreasonable, and said "I don't have to tell you when I'm showing up". The next time, she did message me, but she made a huge performance out of it, behaving like it was a big deal to tell me she was paying a visit soon.

She expected to have all access to us, but our access to her was very restricted. She wouldn't tell me what her college major was, and when a relative told me she got very angry.

She used to get very upset when money was spent on me. She once told me that sending me to college was a waste of money because only went for two years and I didn't finish. However, our father would buy her shoes and clothing she'd wear once and forget about. She would discourage him from buying me clothes.

She would often manipulate others to get what she wants. She lacks empathy for other people. When I tried to hold her accountable for mistreating me when we were younger, she said "the way I treated you is the way you treated yourself" . She refuses to take responsibility for her actions.

Is she just a terrible person, or does she display the traits of a psychopath (or a personality disorder)? What do you all think?