Are you legally responsible for the medical bills of your living spouse in PA?

Yes, as a married couple, you are responsible for all expenses incurred by both of you. If the shoe was on the other foot, she would be responsible for your bills. If the billing somehow is in error, call the doctor's billing office and see if they can help regarding the collection agency. Otherwise, hold tight on the collection people: wife can tell them you are working with the original creditor. Ask the Dr. for a copy of the bill and help in solving the issues of non-payment. Then, determine if they sent the claim to the right primary insurance first. You might have to have them bill the remainder to the secondary insurance. Find out from them what the coverage is. It is just a pain in the neck to follow through on all of this stuff; eventually it will get paid. If not, you can also get with the board of insurance. BTW, get the name of each person you call and keep a log.