my cousin wanted to ship with me, what should i do ?

my age : 16
her age : 13

her mother brought her to my family's house because her parents are getting a divorce but she couldn't bring any of her stuff (laptops,phones,etc) so she has been bored lately but i caught her out using my stuff (laptops.phones.musical devices) and she liked them from that point she kept coming to my room constantly and started to tease me sometimes she sit in top of me in porpuse and sometimes she stand in front flashing her butt to me and that is unbearable if this continues i think i'm going to do her but for some reason her mother is doubting me and my sister who's a literal whore btw told me that she and her mother know that i'm harrassing her , i laughed and told if harrassing is a girl being with a boy then non-harrassing is a the literal sexism but don't get me wrong i get why they would say that cuz i was planning to start avoiding her at all costs but damn what's wrong with this girl ? who will tease thier cousin like this ,

listen to this : sometimes when she wanted monies she would suggest a game that is called the gambling wish , as the name suggest the first player bet his monies and the other one bets a wish so when i win she has to do something that i wish , of couse my wish was to do something insead of me cuz of how lazy i am but she posed her in a such a sexual way that was making my body