You were named in the complaint because you are someone with, arguably, an interest in the property (for all they know, you could still be living there). For this reason, complaints will also name "unknown heirs and legatees" or "unknown occupants." So, assuming it is true you did not sign a note or assume the mortgage in some fashion, you will not be held liable for the debt.
This post is for general purposes only and is not intended to create an attorney-client relationship. Please consult an attorney for specific legal advice for your situation.
You need to contact a local real estate attorney to protect your credit. You also need to pull your credit and make sure it has not affected it in a negative way. If it has you need to do a QWR with the mortgage company.
Arnold & Wadsworth