"I took over my sister's lease"
That's not what happened here. You don't seem to think it matters much who is on the lease, but it's the ONLY thing that matters. Also, based on your comments, it sounds like this wasn't you doing her a favor. It was more like the reverse. I don't know how you ended up with all these people living with you not paying rent, but clearly some bad decisions were made along the way to get you into this mess. Most people just rent the place on their own and don't take in freeloaders.
I don't know what to tell you, but if this is your only living option, then of course you need to do what she says. It would be very different if you could get out on your own, but it doesn't sound like that. But for your own sake, stop trying to assert your "authority". You don't have any.