What will be first reaction when Cersei finds out about Dany’s pregnacy? What will be first reaction when Cersei finds out about Dany’s pregnacy? 

If Cersei isn’t pregnant anymore  she hasn’t heir

If Dany is pregnant it means that she has a heir .  And this baby is heir of iron throne.
Practically this baby is the most important person around Westeros . 

What will be her reaction.