S.T.
perhaps the divorce is not being handled as well as you think. many children "act out" for attention. Or, they see that it makes their parents talk and they want that more than anything. Many children feel responsible for the break up and act out in different ways. Children are not as resilient as everyone thinks. Their little lives are torn apart, their security is gone.... it takes a while to adjust and accept. The 5 year old is perhaps more understanding, or just handling in a different way. Reassurance that it is not his fault, and how much you love him and are proud of him.