I?m [15F] getting **** for sharing a bed with my [10F] sister

Tl;dr: New friends at school talking **** about my home life. Just want them to stop and leave me alone.
For context, I moved to the states pretty recently and invited a friend (Steph) from school over. I was pretty nervous cause I live in a two bedroom apartment complex and most of the people I met at school are pretty well off. I?ve been to other people?s houses before, so my mom wanted me to invite someone over to ours.
I really wish I never tried to make friends. I share my room with my little sister, I never saw it as a problem or as unusual before and neither of us have an issue with it, but ever since Steph came over other people have been making fun of me ?sleeping with my sister?.
I dont even know why theyre making fun of me but I?m not interested in having friends or keeping these people around. How do I get them to stop saying disgusting things though?
Edit: Sorry for not responding (I had hw) but thank you for all of your thoughtful replies. I didnt realize how hard I was taking it but I was literally crying while reading the responses...and everyone had different life stories!

1. Sorry if it was confusing, sharing a room always meant one large bed in the room so I didnt even think to clarify that.
2. I invited her over on Saturday after hanging out with other people and then a mutual friend tagged a picture of me on Sunday on someone?s ?food baby? with the caption ?OP?s future bf?. On Monday at lunch someone asked me about sharing a room with my sister, and how I could live with everyone on top of each other and wasnt it annoying. I tried to let it go. What made me write this post was because today during sex ed, a classmate said I shouldn't participate in the robot doll project because I?m a ?pedo?.

Obviously theyre all joking or w/e but I just feel stupid for even trying with these people. They?ll probably forget it by next week, but I dont trust them anymore. So I?ll just take your advice, keep my head down, hope to meet a better group and not invite people to my house anymore.


Source.