I had my ex. threaten my lawyer in my presence and his attorney's presence. Is this against the law?
Aside from the fact that no one here knows what the "threat" was, the obvious answer is to ask your lawyer.
Obviously no one can answer the question you posted. You left out what was said or done and the context in which it was said.
It seems very curious that you are not asking the question to the one person who will not only know the answer but will know what to do - your attorney.