This does not appear to be illegal, creepy but not illegal. Now that you have been served, you must respond by securing a local divorce attorney immediately. If you want to make sure your ex stays away, consider a temporary restraining order.
The divorce pleadings cannot be served by your spouse, but there's no problem with your spouse giving the process server a lift. If you were legally served, your signature is not necessary. You should immediately consult with a good attorney. It’s always best to consult with a good family law attorney to discuss the details before you act. See my AVVO Legal Guides on divorce and service of pleadings for more information about the legal issues raised by your inquiry. Click on my photo. On my AVVO home page click on "View Contributions" or scroll down further and click on "Legal Guides." Scroll down the list of my 29 Legal Guides and select the topics relevant to your question. If you like my answer and Legal Guides, please make sure you mark them as “helpful.”
This AVVO Answer is provided for general educational purposes only. By using or participating in this site you agree and understand that there is no attorney client relationship between you and the attorney responding, and no attorney-client confidentiality. The law changes frequently, and varies from jurisdiction to jurisdiction. The information provided in this Answer is general in nature and may not apply to the factual circumstances described in your question. The applicable law and the appropriate answer may be different in the State or States where the relevant facts occurred. For a definitive answer you should seek legal advice from an attorney who (1) is licensed to practice in the state which has jurisdiction; (2) has experience in the area of law you are asking about, and (3) has been retained as your attorney for representation or consultation. Your question and the attorney’s answer may be used for promotional or educational purposes