Your son you raised for 10 years isn't really your kid?

Ok so a friend of mine( her husband works with my husband so not really close but we are friends) who was living in the middle east and gave birth there, found out that the day she gave birth some how her birth son was mixed with another baby boy which she took home and raised.. The other kid's parents took her baby home and raised him. Her birth son turns out to have autism.. She raised the boy for 10 years and its so hard to give him up but also hard to give up her birth son since she knows the truth and vice versa for the other parents.. I'm very shocked and confused and wasn't able to ask many questions but I personally wouldn't know what to do.. What would you ladies do if god forbid something like that happened to you?