You ask such an imortant set of questions. Bless you for caring so much about these kids. As Mr, Littman has written, however, you really have no place in the children's lives legally if your spouse passes.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.
The long and short answer is that a step parent rarely has legal rights to a child. When the parent dies, the other parent usually assumes care for the child. If she were not to do so, you would be in a different position. You can only adopt him if the biological mother is willing to relinquish her legal rights or if she abandons him. It sounds like this has not happened. There is no such thing as a permanent step parent. Good luck to you
Step-parents do not have the same legal status as legal parents. Your relationship with the child's mother will probably benefit if you keep this in mind. If your husband passes away, the child will likely go to live with his mother. If she allowed him to stay with you for six months with the father gone, you would gain standing to seek a custody order. However, if that did not happen, you would have no legal rights.
You can reach Harkess & Salter LLC at (303) 531-5380 or info@Harkess-Salter.com. Stephen Harkess is an attorney licensed in the state and federal courts of Colorado. This answer is for general information only and does not create an attorney client relationship between Stephen Harkess or Harkess & Salter LLC and any person. You should schedule a consultation with an attorney to discuss the specifics of your legal issues.