If I file for bankruptcy, can he come after me for non-payment of his bills?

If the bills are for treatment that occurred after your divorce, you should not be liable for them and should make this clear to the bill collectors coming after you and to his mother and/or sister. Perhaps you need to show them the date of a divorce decree. If the bills after from dates prior to your divorce decree and such decree says that you have to pay them, you may be stuck with them despite a bankruptcy. I think the latter is unlikely, though. If the decree does not say you are responsible, a bankruptcy discharge would eliminate your personal liability for pre- or post-divorce collections. In the end, you need to consult a bankruptcy expert to go over your specific facts and provide you relevant advice on what to do or not to do.

You are not responsible. Tell the hospitals you are divorced, and that a fraud has been perpetrated on them.

If his medical debts were incurred after your divorce, you should not be legally responsible for them.

With or without bankruptcy, you are not responsible for paying an ex spouse?s medical bills made after your divorce became final. However, the hospital and other medical providers are unlikely to know about your divorce or the cancellation of insurance benefits provided through your employer unless you TELL THEM. Do not attempt to resolve this by phone or email. The professional way to communicate is always by US mail, with a copy of the final divorce papers showing the legal situation.

Bankruptcy eliminates all your bills (except specific exclusions like student loans and child support), so a former spouse's medical bills regardless of whether you signed as a responsible party, would be eliminated.

Ordinarily you are not responsible for debts incurred after you were divorced. If you file a bankruptcy, it is likely that debts allocated to you by the divorce court would not be dischargeable in a bankruptcy. But there are some conflicting published legal opinions on that question, and some technical distinctions between the two federal statutes which could render such debts dischargeable. So you would do well to consult a lawyer in your locality who is familiar with the Bankruptcy Court for your federal district.