First, if you no show, it will not affect the remaining four. Each passenger has his own e-ticket and the PNR is simply an administrative convenience (especially where everyone has status for purposes of a bag if you are checking at all).
Second, you then have a decision to make. If you do nothing and the EWR-ORD flight is neither cancelled not significantly delayed, you will have no showed and your return to EWR will be cancelled because of the no show. At that point, you will need to purchase a new ticket ORD-EWR. Depending on whether you meet advance purchase requirements and fare bucket availability, that return might be dirt cheap or eye-poppingly expensive. No way to predict in advance. If the flight is delayed or cancelled, you may then cancel your outbound without fee. If you do cancel your outbound and your ticket is thus rebooked, there is at least a $200 change fee and there may be a fare difference as well.
The bottom line is that what you choose to do won't affect your family, but there is no good way of predicting what will happen to you. Thus, it all depends on risk tolerance.