If he is making threats, now is the time to get a lawyer involved. I would check with your local family court, and see what might be available for free advice, to begin with. You do not need this to potentially turn into a custodial-interference case. Look after yourself, and good luck!

Family Lawyers are best when kids are concerned. He may try to get full custody to avoid future child support action. Lots of Dads are doing it these days as the child support laws have gotten tougher. It does not seem like he is a good candidate for custody based on what you have written. Tell the Lawyer what you have written here about his lack of involvement in the past with your son. It may be that since your son is older now and out of the high needs/diaper bottle stage and all that hard work is done, he figures he will have it easier. Best wishes to you.