Moving away sounds like it'd be for the best. And getting some counseling for your sister. It's really excessive, but desperate times calls for desperate measures.
However, you should talk to an authority figure about this, even if you need to go to the police or something first. Visit your principal and talk with them about this.
But, never, ever, let people shame you into not being the kind of person you are. If you liked that shirt you wore, keep wearing it and ignore anyone that tries to stop you or insult you out of wearing it. There's nothing wrong with who you are or your interests (from what I can tell about you).