The options you mention are available IF you filed bankruptcy with your wife. If she filed by herself and you were jointly liable for the debt, then you still owe it and the lawsuit would be allowed.
If the lawsuit is against your wife and the debt was incurred prior to the bankruptcy and the debt was listed in her petition, then you should fax to creditor's counsel copy of discharge order. If they don't immediately dismiss the case, remove all negative information from credit report, then you should file an answer to the lawsuit with copy of discharge order stating as defense that this debt was discharged and case should be dismissed. You can also re-open the BK case and file motion for sanctions because creditor has violated discharge order.
If the debt was incurred prior to bk filing but was not included in the BK, then creditor did not receive notice. If will still be discharged if the BK case was a no-asset chapter 7 case. Then do same as above except can't sanction creditor since they had no notice.
If debt was incurred after filing of BK, then it was not part of BK case and was not discharged. You can obtain verification of debt (invoices etc) through creditor's counsel if not already attached to the complaint filed with the court.
If lawsuit is filed against you, not your wife, and you were not a party to the BK petition, and you are liable for the debt then creditor can sue you and you cannot claim wife's discharge as a defense.
The wording of the letter sounds strange. Why would a law firm have to learn of a suit filed? Are they offering to perhaps represent you? Maybe they are suing you themselves. ?
If the discharge was obtained, you could either reopen your bankruptcy case, or use it as a defense (with a counterclaim for collection violation in state court.
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