Would appreciate some perspective

I'm going to try to keep this as brief as possible , I'm having a hard time with my sister and I keep doubting that it's me who's troubled but I'm not sure , hence why I'm here . So generally speaking she's just always interfering in other people's personal matters for one reason or another , that's mostly none of my business except when I fall as a victim for this kind of toxic attitude of hers, so anyway here's the most recent encounter that's kind of really itching me right now , so I'm sitting in the living room studying on my laptop and she's just lying on the couch across from me , then out of the blue she asks about my grades in college in the first semester ( I attend a private university and the fees are a bit hefty, so I need to get high grades in order to get discounts every year) , so I told her that apart from 2 B+s in couple of in class tests , I got straight As in the rest of everything , she replies saying "well you gotta be careful, you know you need that discount", anyway the conversation goes on for a while , I get uncomfortable with her interrogating me about my academic performance and I tell her to stop talking about it , she refuses and keeps telling that I'm running away from the conversation because I know that I'm not studying well, although I know quite well the opposite of that , at this moment I just kinda lose it and I tell her that she keeps judging other people so that she can feel better about herself; she's 27 , still hasn't moved out because she spent 10 years in college (the difference is that she attended a public college that was much cheaper), I got into a private one because of a little bit of a long story that I don't feel like telling right now(it wasn't my choice quite briefly), anyway I get frustrated even further and tell her that my academic performance and my college fees is none of her business and that she's an adult who's no longer relying on my parents financially (she kinda is currently because she quit a Medical Rep job that she couldn't stand) .

My mom finally comes in and tells her to end it, so I know I freaked out when I really shouldn't have, I mean she's always doing this and I guess you could argue that she didn't necessarily mean anything by it, but because of my knowledge of her, her ways and just her way of talking, it kinda infuriated me for some reason; I'm really doing all I can here and well I guess I've gone on about this for long enough , thanks to whoever took the time to read it and sorry if it sounds kinda stupid, there are other similar incidents with my mom and my other sister (she once kept yelling frantically at my mother because there wasn't any food that she liked in the house and only some left overs were in the fridge) and this kinda makes it harder for me to stand her honestly.

When people rag at me like she did to you, my inclination is to say - who asked you? If I want you opinion I will ask for it.

Then change the subject or go silent or leave the room. Some people like to argue and some are right fighters. Dont let her goad you into a verbal exchange you know won't end well.

Yeah you're definitely right , it's just that she keeps talking and talking and I feel sort of assaulted mentally when she does that and just automatically turn to defense mode, I guess should learn to just ignore or keep nodding as if I'm as lazy and careless as she's always trying to prove me so that she can get the satisfaction of winning this ridiculous battle and I could get the satisfaction of her leaving me alone :(

The best answers for someone who always likes to sir the pot is a question. For example "why do you ask"? and/or change the subject, "what are you doing this weekend"? Don't take the bait. Don't get trapped in their drama. They get a rise out of this nonsense and watching people lose it in front of them.

Still one of my favorite sayings: You don't have to attend every argument you're invited to.

:)

Just shut her down rather than continuing to engage her. "I have no interest in discussing xxx with you. If you would like, we can talk about something else, but I will not continue to participate in a conversation about this." Then don't.