Let's start with the end and work backwards.  In order for your new husband to adopt your children you will either have t have your ex husband's parental rights terminated or he can give them up voluntarily.  Termination means that you and the children have no rights as to your ex monetarily: you in support or them in inheritance.  Doing time in prison does not necessarily automatically terminate parental rights, unless the reason for your going to prison has to do with an offense against the child or children and that is only in some states.  I would seek help from ana ttorney in your area on this matter.  Good luck.