I let my sister-in-law use my pool every summer for her kids’ parties. When I asked to borrow her tent for camping, she sneered: “Get your own stuff—you’re so pathetic.” My mother-in-law chuckled: “You shouldn’t expect too much if you’re always asking.” My husband added: “Stop being such a freeloader.” I came back from my trip to find my pool drained and damaged. Her note read: “Pool parties are over—maybe this will teach you not to rely on others.” I stayed silent, but what I did next left them