Yes it has all the earmarks of a scam, it is not the way a legitimate debt collector would proceed.
You can file a complaint with your state attorney general. Or use the link below to file a complaint and find out about your rights with debt collectors.
I am not your attorney unless you and I have signed a retainer agreement. What I am saying is not legal advice. Do not act on this information without engaging my services, this is for consideration only.
If this is a real debt they should be able to validate it for you. If they initiated a lawsuit and there is in fact a hearing, you should have been given proper notice but I suspect this is also false however, you should look up your name on a local county court website to be sure that you are not a party to a lawsuit. Lastly, you are well within your right to request that they stop contacting you or you may request that the only contact they have with you be in writing. Once you give them this ultimatum, a scam collector may change their minds about creating evidence that could lead to counter lawsuit or violations of debt collection acts.
This has the earmarks of improper debt collection. If it is your account (and not hers), the collector should not be disclosing information about the debt to your ex-mother in law. If you have indeed been sued, you should have received notice through service of process. If there is a hearing, you should have received notice of that as well. However, it is a good idea to go to the court's website to see if your name comes up in a party search. If you have not been sued, the collector should not be making references to a hearing. Depending on when the last payment on the account occurred, it may be beyond the statute of limitations.
This response is not intended as legal advice, and does not create an attorney-client relationship. Such information is intended for general informational purposes only and should be used only as a starting point for addressing your legal issues. This posting is not a substitute for an in-person or telephone consultation with an attorney licensed to practice in your jurisdiction about your specific legal issue, and you should not rely upon such information. This posting is not confidential and is not subject to attorney-client privilege.