As parents there are a lot of times when we are dealing with stressful situations that we want to"protect" our children from. This might be work, health, or relationships related. The first thing to know is that children are impacted by anything that impacts you. Therefore when a child is upset it is sometimes difficult to know if they are reacting to the normal things that impact a child of that age or if they are feeling the stress from your situation.
Next, know that children find comfort in the consistent and familiar. Routines and expectations provide the structure within which children live their lives. Try to keep things as "normal" as possible. In addition to that be sensitive to the need to listen more and talk less. Children need you more than they need your directions. Allow yourself a "time-out" if you need a break.
There are also some great children's books on a variety of topics that are good conversation starters. Keep in mind that you need to read through the whole book and make the best choice rather than just selecting a book because it deals with that topic. It would not work, for instance to read a book about divorce that ends with the family living happily separate if that is not the real outcome. Children will remember the story longer than your words or, "but that won't happen to us."