Hey popi, Sorry to hear that you’re in a tough situation with your sister. I think it’s important for you to understand that her comments and criticism aren’t about you. They’re about her. Like Samuel already says, it seems like she’s feeling insecure or unhappy and takes it out on you. Maybe you can have compassion for her about this. Understand that she’s behaving towards you in this way not because she wants to harm you but because she is suffering.
Of course this doesn’t mean that you should just accept her behaviour. Live your life and ignore her negative remarks. Do I understand correctly that you live together? That makes it harder of course. But do you keep your distance from her at university? Like Samuel, I’d suggest you tell her that her behaviour is hurtful and that you don’t wish to talk to her if she speaks to you like this. But show her your love and maybe you will seem less threatening to her and she may stop being so mean.