Care and Feeding Photo illustration by Slate. Photo by SerrNovik/iStock/Getty Images Plus and Albina Gavrilovic/iStock/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 husband’s parents went through a bitter divorce last year after his dad left his mom for a woman who is a year younger than my sister-in-law. Our son will be turning 5 in a little over a month, and my in-laws cannot be in the same room together. When I suggested to my mother-in-law that her ex be there without the side piece and keep his distance from her, she vowed he would be wearing the cake if she saw him. Obviously, we would like for both of them to be there for the occasion, but not if it results in an ugly scene. Can you offer any suggestions?…