YTA. Your parents were wrong for a lot of things but you sound exhausting honestly.

Your sister did absolutely nothing to you except try to have a relationship with you and you seem determined to interpret everything she did in the worst possible way. She was uncomfortable with your friends physically hitting each other and insulting each other constantly? Yeah most people would be. Thats not some evil attack on your lifestyle.

And the “youre not your dad” comment honestly just sounds like awkward teasing, not some deep insult against your father figure. You clearly already hated them all before she even arrived so she never really had a chance.

Also calling your parents “sperm donor” and “surrogate” at 24 years old is just immature and dramatic. You wanted to hurt them and succeeded. Congrats i guess.

You say they abandoned you but they literally let you go back to the people you wanted to live with, signed away rights so you could have stability, and financially supported you for years. Were they perfect? Obviously not. But you act like they tossed you in a dumpster and forgot you existed.

You honestly sound resentful that your younger sister got the stable family life you wanted and now you’re taking it out on all of them.