Answer: Any time someone threatens you directly, you have the right to file for a civil harassment restraining order. Click here to read an article on how the process works.
Your situation is a little tricky because there have been no threats made against your son, so the court cannot issue an order protecting him. During the times you have custody, any "stay away" orders you receive will also protect your son. During the times that your ex-wife has custody, you will need to address this issue with the judge that is handling your divorce matter. Unfortunatley, you ex-wife's suicide threats are inadmissible heresay and have nothing to do with the threats made against you by her boyfriend.
You suggest that you file for the harassment restraining order and then discuss the custody issues with a family law attorney to see if it is possible to keep this person away from your son.
About the Author: Carl H. Starrett II has been a licensed attorney since 1993 and is a member in good standing with the California State Bar and the San Diego County Bar Association. Mr. Starrett practices in the areas of bankruptcy, business litigation, construction, corporate planning and debt collection.