Legal Question in Family Law in Illinois

Unless the step-mother poses an endangerment to the children, a court will not limit her access.

You can but you better be prepared for extended litigation, high attorney fees, the appointment of an attorney for the child and have proof that your ex seriously endangers the welfare of your children. This assumes that when you say "my children" you are referring to children which the two of you have together. If "my children" means children of which you are the only parent then you can w/o much of a problem get an order baring your ex from contact.