You can go to the biometric alone. Make sure you bring your ID and the biometric appointment letter. During the appointment, the service will take a picture of you. They will also check your fingerprint.
This has nothing to do with your "illegal" stay. The service will check your criminal history.
You can schedule an info pass and get a temporary green card stamp. You will need to explain your plan to travel abroad soon, and how you did not get the green card despite what the tracking number says. I don't know about CO, but some jurisdiction, officers are reluctant to stamp unless you give really good reasoning (like here where you have plan to travel.)
After that, file I-90 to replace the green card. You need to pay fee as well. I know this is not your fault. However, it is not the...
You may want to consult with a family law attorney in California. In many states, a person's immigration status is irrelevant therefore a person is able to obtain a court order against ex-partner to pay.