Ladies I need help

Ladies my husband of two months. Has a godson who no one is taking care of the child the child is almost 4 and is not potty trained and he can not talk either. My husband asked to adopt him but she said no you can not have custody of him but you can raise him full time and he doesn’t have a father. I want my spouse to walk away from this toxic situation but what else to do? Trust me it’s more to the story