NTA. Your sister deserved what you dished out for being a spoiled, entitled brat. Did you cross the line? Maybe a little, but things are said in the heat of the moment. It’s not like you blew up at her out of the blue. She made multiple attempts to break family tradition by talking to you and your parents over and over again, clearly not getting the message. And despite all of those conversations and despite your parents breaking their own tradition by offering to buy her a necklace in lieu of the ring to shut her up (which is tantamount to bribery), she still insisted on pressing the issue.

Don’t listen to all these people saying ESH. You and your parents made fair attempts to appease your selfish sibling and it didn’t work. Your anger was justified. I won’t speak to the language you used because it’s still your parents house, but no. You are Not The Asshole.