Husbands sister in law just moved in!!

So my husband has a brother who is living with us he is currently still a senior in high and he decided to tell his gf who just turned 18 to move in with us and I didn’t find it a a problem as long as she pays bills. One thing I hate is her getting out god the shower basically naked she only had a itty bitty towel around her and doesn’t seem to care.. also she is always wearing booty shorts that basically show her ass. I about had it and I feel like kicking her out Idk what I should do because I feel it’s disrespectful towards me and my husband. What do y’all think ladies ?