This is a sticky sort of situation. Legally, your husband is only required to provide for his biological children or any he legally adopts. You can try to pass off your husband as the biological father (but he could figure it out, sue for a paternity test, find out he's not the father, and therefore not have to care for the child). You can confess to your husband and if the biological father is willing to give up his legal rights (and therefore responsibility to support the child) your husband can adopt the child.
