I am a Court Appointed Special Advocate (CASA) for children in foster care.

I'm not going to tell you what I think you should do because your situation is very complex.

I will tell you where you stand from a legal standpoint regarding the child.

You have no legal rights to this child. You need a paternity test to make sure this man is in actuality the biological father. His parental rights so far are intact. The best you can do is petition the court to grant you the same custody rights as your fiance. That way, should anything happen to mom, he can't come and just take the kid. The only way you can adopt the child is if the biological father gives up his parental rights or if he is a danger to the child, his rights may be revoked.

As far as what to tell the child? He/she is more resilient than people give them credit for. DO NOT lie to the child about his parentage. He/she doesn't need to know the circumstances of their conception. They just need to know that they are loved and well cared for.

Also, I think considering your situation, you are doing alright for yourself. Communication. Communication. Communication!