At Above The Law, there's some good advice for dealing with difficult opposing counsel by Brian Tannebaum: The Practice: "Dealing with Threatening, Demanding Opposing Counsel"--
Part of the problem is that we’ve all been trained to do things a certain way. Someone writes a letter, you write back. Someone threatens, you threaten back. Someone raises their voice, you speak louder. Why are you doing this? What are you accomplishing?
For solutions to the problem, read the whole post.