Care and Feeding Photo illustration by Slate. Photo by Getty Images Plus. Care and Feeding is Slate’s parenting advice column.  Have a question for Care and Feeding?  Submit it here . Dear Care and Feeding, My sister “Madison” got divorced three months ago. She and my former brother-in-law have two kids who are 3 and 5. Maybe I’m making more of this than it really is, but she has a 24” x 18” picture of her ex in the family room and has been using it as a dart board. The kids see her do it (she even did it when I was there recently and called him every curse word in the book the whole time) along with the unflattering details Madison has drawn on it. Yesterday my niece asked me why her mom hates her dad so much. Should I try speaking to my sister about how her little method of venting her anger is affecting her daughter, or is this something I need to stay out of? —Darts for Daddy Dear Darts,  Those poor kids. Yes, please try to talk some sense into your sister.…