The other day, I came home to my dad’s house (my parents divorced when I was 15) to find my stepmom “Sandra” screaming at my dad and accusing him of cheating on her. When I asked my dad what was going on, he said my stepmom had found make-up stains on the sheets. —What They Don’t Know …Dear Don’t Know,I can imagine how tempting it is to stay quiet and hopefully watch Sandra walk out of your life, but you have to think about the pain that would cause your father. Also, let your dad know that you’re doing this for him, not Sandra (as I imagine he already knows just how you feel about her). —JamilahMore Parenting Advice From SlateMy dad cheated on my mom and is now living in an apartment by himself.