Student loan debt / obligation of spouse

My husband has approx. $350,000 of student loans to pay back. The loans are all in his name only. Some were taken out before we married, some after. What is my obligation as a spouse if we divorce? Will I be liable if he defaults? Does it depend on how long we've been married? And I suppose I should also think about...what if he dies; again, am I liable for those loans? Thank you! -