The general rule is that an almost 15 year old misdemeanor domestic violence conviction should not have any impact on a current custody proceeding, nor could it be used as evidence of guilt with respect to any new charges. In any event, I suggest that you begin to document your boyfriend's ex's threats. For example, if they are written or recorded, save the letters, emails, tapes, etc. Moreover, you may wish to consult with a local attorney to discuss this matter in greater detail so that you can develop a strategy to take pro-active steps to his ex's conduct. Good luck.