Dear Prudence,
My 19-year-old half-sister is currently living with me. Her mother basically drove my sister into a mental breakdown with her unrealistic expectations and forced activities. Once she reached college, my sister realized she hated her major, her life, and herself. She was clinically depressed and borderline suicidal. Her mother told her that she was “weak and useless” and cut her off financially (our father had left us money but only for college, nothing we could use to support ourselves). I offered to take her in for a year, all expenses paid, so she could catch her breath. I have a master’s degree and a great job; one teenager isn’t going to break my budget.
My boyfriend makes “mooch” jokes around my sister, and it has spread to our circle of friends. Despite my warning him to lay off, it still comes up. I don’t want to reveal what actually is going on with my sister and her mental health, but I don’t know how to express how important it is to drop this joke. Last time, I snapped and told my boyfriend to shut up and that he wasn’t funny. It killed the entire mood and affected my sister badly. She doesn’t have any friends yet and spends most of her time volunteering at an animal shelter or with me. How do I get this across to everyone?
—Not a Mooch