well now you more than likely will have to buy a new o2 sensor as well as a new cat and pay whatever it costs to get them installed if you cant do it yourself.

a properly working cat is essential to a well running vehicle in any vehicle with an emissions system.

and just an fyi, cats never commit suicide, something else wrong in the system always kills them, so if you had a bad cat you may want to do some investigating and find out why it died.