Very confused.
You have been a foster parent, working in they system, within the past 13 years (kid was conceived before you were together, so you and your husband have only been together for less than 13 years), yet you have no idea how the system works or even the correct name. And from what you have posted, this was not a one time foster experience, since you said you had to quit because it was getting too hard to send the kids back. Every experienced foster parent I know, knows the system better than the social workers.
You were able to make an appointment and get a DNA test on a MINOR without getting the DFS involved (and you knew they are involved in his life). Within a week of meeting this child. And again, the most important: WITHOUT getting permission from DFS or the courts.
Story is being added to as people question it. Mother has now been talking to alcoholic grandmother for 8 months, yet never told the dad.
Sorry, but after the Leukemia mom and the pregnant mom running to Canada, I am quite suspicious of crazy stories that don't add up.
Hard to believe all of this has gone down in just a week. However, OP, if it is true, I apologize and wish you good luck. Glad you are accepting the child.