Physical activity is a wonderful release. Together you can run, wrestle, race bikes, shoot hoops, etc. Books can be helpful when teaching young children how to accept anger. Be sure that you have read the book first to ensure that the messages are those you find meet your family values. Talk to your local librarian for suggestions.
Older children can use journals or letter or story writing as a way to express themselves.
For the child who is experiencing depression or intense sadness, drawing pictures of past family times, both good and not so good, can open realistic discussions. Looking at pictures of those times, sharing memories of before the divorce, will help children to view both the past and present realistically. Again books may be helpful with younger children. These letters are not mailed or shared. The purpose is solely to enable the child to express his feelings.