Homophobic house sitter?

So I have an extremely homophobic house sitter who always makes snide and very offensive comments towards the GLBTQ community (whenever it is mentioned), which extremely angers me. Also, she usually makes these comments in front of my little sister, who is very young and is influenced by anyone. Could someone help me think of effective ways to explain to our homophobic house sitter that her offensive comments are not appreciated and that she should share her opinions elsewhere? I am having trouble thinking of ways to complain to her (without screaming) since she is very oblivious, and is much older than me, and I do not want to be caught in an extremely awkward situation with her since I see her every day. Help will be appreciated!