Nah she doesn't love him shes taking care of him because of a sense of duty she literally said he was a burden and she hated her parents cuz they left him with her..... so nah she doesn't love him..... it sucks she had to grow up to quickly and sacrificed her childhood ..... but still if she does bad shit then she not nice and if her bro does bad shit he not nice either....
She said her childhood was a burden because she's more of obsessed with the duty their parents left her, she doesn't hate him either, she just asks for the attention she should've gotten when she was young while she was taking care of her brother. And also, the sentence where she claimed to be complaining about the fact they left him with her was meant as an confirmation that she wanted to live her life that she deserved to. Now that she finally got "love" she doesn't want to let go (next week new chapters, which will explain it) it's more like she took care of a dog giving love affection she should've gotten, she doesn't hold a grudge against him, rather than that she's jealous.
I think the sister really luvs her brother and that she is the only one who can take care of him and no one else can. You can tell she cut her hair to make it look like the wig, so that one day she can find out her littles brothers secret.