Need help with landlord!!!?

This is complicated. My landlord is really just the owner of the property. She is also my boyfriend's grandmother, she pretty much raised him, he is used to her babying him, and she is rude and ornery. However she doesnt charge rent but just makes us responsible for our share of bills. Our cats have gotten fleas this summer and it has been difficult to manage because I work two jobs and busy all the time. His granny wants to treat the house and animals with poisons i will not tolerate being exposed to, i prefer natural substances but now she told her grandson she doesnt care she will do it anyway. Dont i have some kind of right to not be exposed to those chemicals against my will? If so who do i call, what do i do? help...