Dude, I'm sorry.

This is not your fault, and your sister is lashing out at the wrong person. Your parents beat her, not you, and they beat you before her, and because they were absolutely miserable shitty excuses for parents, they wouldn't support you during a time you were bullied/harrassed by an ADULT who should know better. Had the parents been parents and/or and the teachers been adults, this wouldn't have happened: your parents created an environment were you weren't supported (and were abused), so you couldn't tell them about the teacher and classmates, who could have been reported: which would happen in a supportive, loving home. Had that happened, or had people been decent, you wouldn't have made the (admittedly bad) decision to vandalize your bully's car.

Here's the thing your sister doesn't get: you are only responsible for your own actions. SHE choose to LIE FOR YOU. Yes, you vandalized the car and left her to get hurt, but she knew she what would happen to her if she took the fall. Did you ask her to? No? Then she decided to take the blame AND all consequences. People know better than to expect stellar decisions from a teen, so while yes, you shouldn't have let her take the blame... you would have gotten worse than what she got. She got a taste of what you went through.

She got expelled, then did bad at public school (which IS possible to do good in). SHE got fired from her job. SHE smokes. How is it your fault?

And as for babysitting and mothering you? Protecting someone from being bullied and abused is admirable and the right thing to do. Yes, she shouldn't have had that role, but your parents were abusive and SHE CHOSE TO FILL IT. Yes, it's unfair for her, but she's completely forgetting that you didn't deserve to have abusive assholes as parents either, or what it has done to you.

She isn't being a good person. She's blaming you. Wait until she gets her head out of fantasy land, and limit contact with her unless she can get past it. This isn't good for you.