Ok so I am confused? Were you married? If so....What does your divorce decree say about the custody of the children, visitation and child support? You didn't know that there is a difference between child custody and child support? Child support means financial support, as in a person (usually the noncustodial parent) pays a set financial amount of money to the custodial parent for the purpose of financially helping to support the child/children. Child custody can be categorized in different ways (example: physical custodial parent is the one who has the physical custody of the child/children Legal: is who has legal custody, as in who makes all of the decisions regarding the child/children, for instance decisions about education or health issues)Sometimes legal custody can be awarded to someone other than a parent (maybe grandparents or someone appointed by the court)Sometimes physical and legal custody go hand in hand and they are both awarded simultaneously. The determination of who has custody of the children is usually addressed in the divorce decree or separation decree. Yes it can change, but the court has to get involved in that. You need to consult with an attorney. All of this is something that you certainly don't want to try to handle on your own without legal counsel. The Ex cannot legally keep the children from you, unless there is a court order that does restrict your visitation with them, but if that exists I don't understand why you aren't aware of it. If he is withholding the children from you and you from them, then he is in violation of the law and in contempt of court. If he is in contempt and found guilty of that, most times the judge will make him pay your attorney and court costs, but again you need to speak to an attorney for guidance on all of this. If you were married, you can get a copy of your divorce decree from the county courthouse where your divorce was finalized. The children are of the age that they can speak for themselves and that goes a long way toward getting this mess untangled.