Dealing with horrible smells...

My sister inlaw hardley ever showers... like maybe once a week twice depending if she decides to leave the house during the week. Well everytime she it on her period I almost die... her smell is so revolting I throw up everytime I have to go to the bathroom after her... I'm currently pregnant 15 weeks tomorrow. I dont want to be rude and tell her but it's so bad I cant stand it... it just makes me so physically sick... she hates me as it is like no joke she wishes I never married her brother... I c as not even talk to her without her getting mad at me. My hubby, son, and I currently live with his parents because we are trying to pay off bills and save up to move out in February. She also lives with us. Shes single and had never dated. Shes 25 and doesnt even have a job. I dont know what to do... I think shes jealous of me or something and that's why she treats me so bad... idk I need to tell her about her smell but I dont want her to try to attack me for real... any advice? Also she never empties the damn trash can full of just her pads... yesterday her damn dog got into the bathroom and had started eating her pads...