Who is Pam from The Great Divorce and what is their importance?

Pam cannot let go of her personal pain and anger over the loss of her son in her earthly life. Her son Michael died young, and she mourned him so absolutely that she neglected her husband and daughter. Now she demands to have Michael with her, but she must learn to love others, and most especially God, before she see him. She feels that this is cruel and unjust and that a mother's love eclipses all other kinds of love.