If someone files for bankruptcy, how long are they protected from creditors?

The lawsuit protection from filing bankruptcy is permanent, you can never sue the husband. You can only sue the wife. The question is whether you can successfully sue the wife. What do you want? Ownership of the property without them, that's possible. I doubt you can win any money from her unless you have a written contract which specifies her obligation to pay for the property.

Debts discharge in bankruptcy cannot EVER be collected. Debts which are accrued during marriage are "community debts" and are discharged to the non-filing spouse. An exception would be in the event your person "re-affirmed" the debt. This is asking a judge to sign off on continuing to pay and is often done on the debtor's primary residence. It would be unlikely to even be attempted in this case. Ideally you would have put a partnership agreement in place which forced the signing over of the other couple's interest in the event of bankruptcy. If they are still on title, you need still need their sign off to sell the property.

If the bankruptcy concluded with a discharge of debts, you can never sue the husband. It is not clear whether you have any basis for suing the wife either. An attorney would need to review your contract in which you purchased this land to say for sure what can be done.