growing up and staying home

Being quarantined here is beyond insanity because living with my boyfriend and his sister is a massive nightmare. I thought I'd seen the worst just by seeing her for more than 10min at a time on the weekend but boy was I wrong. She's a stay at home freeloader and somehow manages to fill our day with complaints about how unfair life is because she can't go out to buy things she wants with others money (she's in her 20's btw). If I have to hear her yelling out stupidity one more day I'm going to lose it.. what's worse is my bf wants me to take the high road rather than tell her to STFU even though he can't stand her either! For now I'll stick to passive aggressive comments lol maybe she'll get the idea to grow tf up already.