First of all: don't give up.
Your wife and stepson do not have to leave the US at this time.
A new, properly filed I-485 with supporting documentation will eventually get them green cards.
You have to be very heavy on evidence in the next filing. USCIS gave excellent tips on how to build a strong case.
Include each and every page of every statement from your joint bank accounts, utility bills showing both names. List your spouse as beneficiary on your retirement plans. Add her and stepson to your health insurance plan.
Annotate each photo with: "Date, location, occasion, names of people on the photo". Only include photos where you have not just wife and stepson, but your family, friends and colleagues together.
Financial comingling is the king of evidence, as you can see. Remember the saying to put the money where your mouth is? This is exactly the situation.
You have to build a stronger much stronger case to overcome any suspicion on USCIS end.